Born in Tokyo in 1939. He graduated from Tokyo University of the Arts, Department of Crafts.
He left Tokyo in 1975 and moved to a wooded area in Mashiko Town, Tochigi Prefecture.
His "14 Forest Mice" and "Korisu Series" have become long-selling not only in Japan but also in France, Germany, Taiwan, etc., and are loved by children all over the world.
He has won the Picture Book Nippon Award for "14 Hiki no Asagohan", the Shogakukan Painting Award for "14 Hiki no Yamaimo", and the Sankei Children's Book Culture Award for "Alone Saishuresha".
A picture book in collaboration with Eric Carle "Where are you going?" "To See My Friend!" Won the American Parents Choice Award.
In 2014, he was awarded Chevalier of the Ordre des Arts et des Lettres from the Government of France.
April 1998 Opened "IwamurakazuO ehon no Oka Museum" in Bato Town, Tochigi Prefecture. Started activities on the theme of picture books, nature, and children. In 2020, he celebrated his 50th anniversary as a picture book writer.