Toshimitsu Imai was born in Kyoto in 1928. After finishing school in 1948, he trained at the Tokyo State Art Academy. Imai's early style of painting is reminiscent of the Fauves. Throughout Imai's career his work was distinguished by an acute sensitivity to colour. In 1951 Imai was awarded the Kansai-Shinseisaku Prize and in 1952 the prize for the best new artist at the 15th Shinseisaku Salon. After his first solo show in Japan, Imai moved to Paris in 1952. There he attended the Académie de la Grande Chaumière and the Sorbonne, where he completed a degree course in medieval history and philosophy. Imai showed paintings in 1953 and 1954 at the Salon de l'Art Sacré. Under the sway of new impressions and influenced by the critic Michel Tapié, Imai switched from representational to abstract art in March 1955. Imai's work can be classified as Informel. By organising a group show in Japan in 1956 and visiting his native country accompanied by Sam Francis and George Mathieu (1957), Toshimitsu Imai played a paramount role in introducing European Abstract art to Japan. From 1956 Imai's own work was sold by Leo Castelli in New York and, from 1957, Galerie Stadler in Paris. The success Imai had with his work at the 1953 São Paulo Biennale and the 1960 Venice Biennale brought him international acclaim, followed by recognition at home in 1962: Imai was awarded a prize at the 5th Exhibition of Japanese Contemporary Art in Tokyo and the Museum of Modern Art in Tokyo bought several of his paintings. However, Imai cannot be pigeon-holed as an abstract artist; he frequently experimented with figurative motifs. After 1970 - Imai was commuting regularly between Paris and Japan by then - he integrated words into his paintings so that they became the support for poems. In 1982 Imai went to Paris while work of his was shown for two years at the Centre Georges Pompidou in Paris and he began to integrate more Japanese elements into his pictures. In 1984 Imai was a co-founder of the Japanese Contemporary Artists' Association (JCAA). In 1988 and 1994 Imai designed labels with floral motifs for a champagne maker.
Toshimitsu Imai was awarded numerous distinctions in France and elsewhere in Europe: in 1991 he was made an honorary citizen of Madrid, in 1992 of Lyon. In 1996 he was made a chevalier de la Légion d'honneur and in 1997 an Officier de l'Ordre des Arts et des Lettres.
In his last work Imai turned to war as his theme, dealing with Japan's attacks on China in the 20th century and the destruction of Hiroshima and its inhabitants at the close of the second world war. Toshimitsu Imai died after a long illness in 2002.