While employed as an assistant at Tokyo Institute of Technology (Tokyo Tech) in Japan, he developed polyacetylene, which has a metallic appearance. This result interested Alan MacDiarmid when MacDiarmid visited TITech in 1975.

In 1976, he was invited to work in the laboratory of Alan MacDiarmid as a post - doctoral fellow at the University of Pennsylvania. The two developed the electrical conductivity of polyacetylene along with American physicist Alan Heeger. In 1977 they discovered that doping with iodine vapor could enhance the conductivity of polyacetylene. The three scientists were awarded the Nobel Prize in Chemistry in 2000 in recognition of the discovery. With regard to the mechanism of electric conduction, it is strongly believed that nonlinear excitations in the form of solitons play a role.

He was born in 1936 in Tokyo, in the family of a military doctor. Around third grade, he moved to Takayama, Gifu, which is the hometown of his mother. In 1961 he graduated from Tokyo Institute of Technology (Tokyo Tech), Chemical engineering department in the School of Science and Engineering. In 1966 he received doctorate from the Chemical engineering department in Graduate School of Science and Engineering at Tokyo Tech. He then obtained the post of assistant in Chemical Resources Laboratory at Tokyo Tech.

In 1976 he became a post - doctoral researcher in the University of Pennsylvania, USA via an invitation by Alan MacDiarmid. In 1979 he was appointed Assistant Professor in University of Tsukuba, Japan. In 1982 he was promoted to Professor at the University of Tsukuba, Japan. In 1991 he became Chairman of the Science and Engineering Department of the Graduate School in University of Tsukuba, Japan. From 1994 to 1997 he was Director of Category #3 group in University of Tsukuba, Japan.

One of his relatives, Hitomi Yoshizawa, is a member of the singing group Morning Musume Morning Girls. He is also related to Naoko Takahashi, the women's marathon gold medalist of the 2000 Summer Olympics.