Born in Mie Prefecture, Japan in 1922. After graduating from Ueno Commercial High School in Mie Prefecture in 1938, Motonaga worked in Osaka aiming to be a manga artist. He studied oil painting at Nakanoshima Institute of Western Painting (now Nakanoshima Art School), a vocational school in Osaka in 1940. Around 1944, Motonaga studied under Mankichi Hamabe, an artist of Western painting, and began to engage in oil painting in earnest. In 1953, he won the Holbein Prize at the 6th Ashiya City Exhibition organized by Ashiya City Art Association. Stimulated by the Ashiya City Exhibition where many abstract paintings were exhibited, he then shifted toward abstract art. In 1955, his work at the 8th exhibition was highly praised by Jiro Yoshihara, and he joined the Gutai Art Association under Yoshihara’s guidance. Including the period when he was in the United States, Motonaga remained a member of the association until its dissolution in 1971. His abstract expression composed of vivid colors and humorous shapes was sometimes described as “Funny Art.” In addition to his paintings, he created many picture books with his wife Etsuko Nakatsuji, and poet Shuntaro Tanikawa. He also expanded his artistic endeavors to include designs for chairs, objects, and a wide range of other works. In 1993, he participated as a member of the Gutai Art Association in the special exhibition “Passage to the East” of the 45th Venice Biennale. Motonaga was awarded the 15th Japan Art Grand Prize in 1983, the Chevalier des Arts et des Lettres (France) in 1988, the Medal with Purple Ribbon in 1991, and the Order of the Rising Sun, Gold Rays with Rosette in 1997. His works are in the collections of MoMA (NY), the Dallas Museum of Art, Museum of Modern Art in Rio de Janeiro, the National Museum of Modern Art, Tokyo, National Museum of Modern Art, Kyoto, National Museum of Art (Osaka), Museum of Contemporary Art, Tokyo, Nakanoshima Museum of Art, Osaka, Hyogo Prefectural Museum of Art, the Ashiya City Museum of Art and History, the Otani Memorial Art Museum, Nishinomiya City, the Mie Prefectural Art Museum, and the Museum of Modern Art, Wakayama, etc. Motonaga passed away in Takarazuka City, Hyogo Prefecture, Japan in 2011.