• Artificial Island Kansai International Airport, 1994
  

It is colloquially known as Kankū (関空) in Japanese.

Kansai opened in 1994 to relieve overcrowding at Osaka International Airport, which is closer to the city of Osaka and now handles only domestic flights. During the 2006 fiscal year, KIX had 116,475 aircraft movements, of which 73,860 were international (31 countries, 71 cities), and 42,615 were domestic (19 cities). The total number of passengers was 16,689,658 of which 11,229,444 were international, and 5,460,214 were domestic, sixth in Japan and second in Osaka area. However, in 2009, airport traffic has fallen by almost 20% in just two years to 13.4 million. In 2010 airport traffic had risen to over 14 million, with international passengers accounting for approximately 10.4 million and domestic passengers accounting for approximately 3.7 million. Freight volume was at 802,162 tonnes total, of which 757,414 t were international (18th in the world), and 44,748 t were domestic. The 4,000 m × 60 m (13,123 ft × 197 ft) second runway was opened on 2 August 2007. Kansai Airport has become an Asian hub, with 499 weekly flights to Asia, 66 weekly flights to Europe and the Middle East, and 35 weekly flights to North America.

• Weekly international passenger flights: 710
• Weekly international freighter flights: 152
• Weekly domestic (passenger and freighter) flights: 495

In the 1960s, when the Kansai region was rapidly losing trade to Tokyo, planners proposed a new airport near Kobe and Osaka. Osaka International Airport, located in the densely populated suburbs of Itami and Toyonaka, was surrounded by buildings; it could not be expanded, and many of its neighbors had filed complaints because of noise pollution problems.

After the protests surrounding New Tokyo International Airport (now Narita International Airport), which was built with expropriated land in a rural part of Chiba Prefecture, planners decided to build the airport offshore. The new airport was part of a number of new developments to revitalize Osaka, which had lost economic and cultural ground to Tokyo for most of the century.

Initially, the airport was planned to be built near Kobe, but the city of Kobe refused the plan, so the airport was moved to a more southerly location on Osaka Bay. There, it could be open 24 hours per day, unlike its predecessor in the city.

A man made island, 4 km (2.5 mi) long and 2.5 km (1.6 mi) wide, was proposed. Engineers needed to overcome the extremely high risks of earthquakes and typhoons (with storm surges of up to 3 m (10 ft)).

Construction started in 1987. The sea wall was finished in 1989 (made of rock and 48,000 tetrahedral concrete blocks). Three mountains were excavated for 21,000,000 m³ (27,000,000 cu yd) of landfill. 10,000 workers and 10 million work hours over three years, using eighty ships, were needed to complete the 30 metre (98 ft) layer of earth over the sea floor and inside the sea wall. In 1990, a three kilometer bridge was completed to connect the island to the mainland at Rinku Town, at a cost of $1 billion. Completion of the artificial island increased the area of Osaka Prefecture just enough to move it past Kagawa Prefecture in size (leaving Kagawa as the smallest by area in Japan).

The bidding and construction of the airport was a source of international trade friction during the late 1980s and early 1990s. Prime Minister Yasuhiro Nakasone responded to American concerns, particularly from Senator Frank Murkowski, that bids would be rigged in Japanese companies' favor by providing special offices for prospective international contractors, which ultimately did little to ease the participation of foreign contractors in the bidding process. Later, foreign airlines complained that two - thirds of the departure hall counter space had been allocated to Japanese carriers, disproportionately to the actual carriage of passengers through the airport.

The island had been predicted to gradually sink as the weight of the material used for construction would cause it to compress. However,  the island sunk faster than predicted. The project then became the most expensive civil works project in modern history after twenty years of planning, three years of construction and several billion dollars of investment. Much of what was learned went into the successful artificial islands in silt deposits for New Kitakyushu Airport, Kobe Airport and Chūbu Centrair International Airport. The lessons of Kansai Airport were also applied in the construction of Hong Kong International Airport.

In 1991, the terminal construction commenced. To compensate for the sinking of the island, adjustable columns were designed to support the terminal building. These could be extended by inserting thick metal plates at their bases. Government officials proposed reducing the length of the terminal to cut costs, but architect Renzo Piano insisted on keeping the terminal at its full planned length. The airport opened in 1994.

On 17 January 1995, Japan was struck by the Kobe earthquake, whose epicenter was about 20 km (12 mi) away from KIX and killed 6,434 people on Japan's main island of Honshū. Due to its earthquake engineering, the airport emerged unscathed, mostly due to the use of sliding joints. Even the glass in the windows remained intact. Later, in 1998, the airport survived a typhoon with wind speeds of up to 200 km/h (120 mph).

On 19 April 2001, the airport was one of ten structures given the "Civil Engineering Monument of the Millennium" award by the American Society of Civil Engineers.

The total cost of Kansai Airport so far is $20 billion. This includes land reclamation, two runways, terminal and facilities. Most additional costs were initially due to the island sinking, expected due to the soft soils of Osaka Bay. After construction the rate of sinking was considered so severe that the airport was widely criticized as a geotechnical engineering disaster. The sink rate has since fallen from 50 cm (20 in) during 1994 to 7 cm (2.8 in) in 2008.

Opened on 4 September 1994, the airport serves as a hub for several airlines such as All Nippon Airways, Japan Airlines and Nippon Cargo Airlines. It is the international gateway for Japan's Kansai region, which contains the major cities of Kyoto, Kobe and Osaka. Other Kansai domestic flights fly from the older but more conveniently located Osaka International Airport in Itami, or from the newer Kobe Airport.

The airport had been deeply in debt, losing $560 million in interest every year. Airlines had been kept away by high landing fees (about $7,500 for a Boeing 747), the second most expensive in the world after Narita's. In the early years of the airport's operation, excessive terminal rent and utility bills for on-site concessions also drove up operating costs: some estimates before opening held that a cup of coffee would have to cost US$10. Osaka business owners pressed the government to take a greater burden of the construction cost to keep the airport attractive to passengers and airlines. Nowadays, after deep discounts, the number of flights are increasing.

On 17 February 2005, Chubu Centrair International Airport opened in Nagoya, just east of Osaka. The opening of the airport was expected to increase competition between Japan's international airports. Despite this, passenger totals were up 11% in 2005 over 2004, and international passengers increased to 3.06 million in 2006, up 10% over 2005. Adding to the competition was the opening of Kobe Airport, less than 25 km (16 mi) away, in 2006 and the lengthening of the runway at Tokushima Airport in Shikoku in 2007.

The main rationale behind the expansions is to compete with Incheon International Airport and Hong Kong International Airport as a gateway to Asia, as Tokyo area airports are severely congested. However, with the regional trend in open skies agreements being signed, it is possible that all airports can see increases in traffic.

Kansai has been marketed as an alternative to Narita Airport for international travelers from the Greater Tokyo Area. By flying to Kansai from Haneda Airport and connecting to international flights there, travelers can save the additional time required to get to Narita: up to one and a half hours for many residents of Kanagawa Prefecture and southern Tokyo. Due to the time limited nature of Haneda's new long haul international slots this will remain a viable option for daytime travelers.

The airport was at its limit during peak times, owing especially to freight flights, so a portion of Phase II expansion — the second runway — was made a priority. Thus, in 2003, believing that the sinking problem was almost over, the airport operators started to construct a 4,000 m (13,000 ft) second runway and terminal.

The second runway opened on 2 August 2007, but without the originally planned terminal portion, now postponed to a later date. This lowered the project cost to JPY¥910 billion (approx. US$8 billion), saving ¥650 billion from the first estimate. The additional runway development, which was opened in time for the IAAF world athletics championships in Osaka, has expanded the airport size to 10.5 km² (4.1 sq mi).

Further into the future, the airport is planning to construct a new terminal building (scheduled to open in late 2012), several aprons, a third runway (06C / 24C) with a length of 3,500 m (11,483 ft), a new cargo terminal and expanding the airport size to 13 km² (5.0 sq mi). However, the Japanese Government is postponing these plans for economic reasons. The new runway is only used for landings when there are incidents prohibiting take off use of runway A.

The airport now expects to handle 129,000 flights during the year 2007, an increase of 11% compared to 2006 figures of 116,475 flights. The new runway allowed the airport to start 24 hour operations in September 2007.

Since July 2008, Osaka Prefecture governor Toru Hashimoto has been a vocal critic of Itami Airport, arguing that the Chuo Shinkansen maglev line will make much of its domestic role irrelevant, and that its domestic functions should be transferred to Kansai Airport in conjunction with upgraded high speed access to Kansai from central Osaka. In 2009, Hashimoto also publicly proposed moving the functions of Marine Corps Air Station Futenma to Kansai Airport as a possible solution for the political crisis surrounding the base.

In May 2011, the Diet of Japan passed legislation to form a new Kansai International Airport Corporation using the state's existing equity stake in Kansai Airport and its property holdings at Itami Airport. The move was aimed at offsetting Kansai Airport's debt burden.

The merger of the Itami and Kansai airport authorities was completed in July 2012. Shortly following the merger, Kansai Airport announced a 5% reduction in landing fees effective October 2012, with additional reductions during overnight hours when the airport is underutilized, and further discounts planned for the future, including subsidies for new airlines and routes. These moves were intended to bring Kansai's fees closer to the level of Narita International Airport, where landing fees are around 20% lower than Kansai's, and to improve competitiveness with other Asian hubs such as Incheon International Airport in Korea.

Terminal 1
The main KIX passenger Terminal l is a single four story building designed by Renzo Piano Building Workshop (Renzo Piano and Noriaki Okabe) and has a gross floor space of 296,043 square meters (3,186,580 sq ft). It is the longest airport terminal in the world, at a total length of 1.7 km (1.1 mi) from end to end. It has a sophisticated people mover system called the Wing Shuttle, which moves passengers from one end of the pier to the other.

The terminal's roof is shaped like an airfoil. This shape is used to promote air circulation through the building: giant air conditioning ducts blow air upwards at one side of the terminal, circulate the air across the curvature of the ceiling, and collect the air through intakes at the other side. Mobiles are suspended in the ticketing hall to take advantage of the flowing air.

The ticketing hall overlooks the international departures concourse, and the two are separated by a glass partition. During Kansai's early days, visitors were known to throw objects over the partition to friends in the corridor below. The partition was eventually modified to halt this practice.

Terminal 2
Terminal 2 is a low cost carrier terminal designed to attract more LCC's by providing lower landing fees than terminal 1. Similar to Singapore's Changi International Airport's low cost terminal, the terminal is basic and currently only serves Japan's Peach Air. Currently this terminal is not directly accessible by train. Rather if arriving by train, upon arrival at Kansai International Airport's train station there is a free shuttle bus that will transport passengers to Terminal 2.

The second floor of the Passenger Terminal Building is used for domestic departures and arrivals. All ticketing, boarding, and baggage claim are handled on the second floor. International arrivals go to immigration and baggage claim on the first floor. International departures are ticketed on the fourth floor and board from the third floor.

Kansai International Airport is connected only by the Sky Gate Bridge R, a road / railroad bridge to Rinku Town and the mainland. The lower railroad level of the bridge is used by two railroad operators: West Japan Railway (JR West) and Nankai Electric Railway.

JR West operates Haruka, the limited express train services for Kansai Airport Station from Tennōji, Shin - Ōsaka and Kyoto Station. JR West also offers "Kansai Airport Rapid" services for Kansai Airport Station from Ōsaka and Kyōbashi Station, as well as several stations on the way. Various connections, such as buses, subways, trams, and other railroads, are available at each station.

Nankai operates rapi:t, a limited express train service to Namba Station on the southern edge of downtown Osaka. Subway connections are available at Namba and Tengachaya Station.

Railroad plans were drawn up in the late 1980s for an underwater railway connecting Kansai Airport to downtown Kobe and Kobe Airport, although the extremely high cost of the project led to its indefinite postponement.

Kansai Airport Transportation Enterprise and other bus operators offer scheduled express bus services, called "Airport Limousines", for Kansai International Airport.

Two six story parking structures, called P1 and P2, are located above a railroad terminal station, while the other two level parking facilities, called P3 and P4, are situated next to "Aeroplaza", a hotel complex.

The airport is only accessible from the Sky Gate Bridge R, a part of Kansai Airport Expressway. The expressway immediately connects to Hanshin Expressways Route 5, "Wangan Route", and Hanwa Expressway.

In July 2007 a high speed ferry service (run by Kaijo Access Co.) began operating between Kobe Airport and KIX. The journey takes about thirty minutes.

Previous services to Sumoto on Awaji Island and to Tokushima have been discontinued.