As the Kakitsu War occurred and his father, Yoshinori, was assassinated by the vassal Mitsusuke AKAMATSU in 1441, he succeeded to the shogunate at the age of nine supported by Mochiyuki HOSOKAWA and others and became the seventh Shogun.
嘉吉元年（1441年）、嘉吉の乱が起こり、父の義教が家臣の赤松満祐により暗殺されたため、嘉吉2年（1442年）に細川持之らに擁されて9歳で将軍職を継ぎ、第7代将軍となった。