Born the fourth son of Shiba Takatsune. The Shiba were leading Ashikaga kin and later one of the three kanrei houses. Favored by his father from childhood, he was set early on a path to the bakufu's center.
At only thirteen he became bakufu steward (later called kanrei), promoted by his father's backing. He also held the shugo post of Etchu. Young for such office, he was supported in practice by his father and retainers.
When Takatsune fell in conflict with Hosokawa Yoriyuki and others, Yoshimasa too was driven from the capital to Echizen. The house's survival was briefly in doubt, but he was pardoned and restored two years later. Early setbacks shaped his later caution.
He was central in the Koryaku Coup that drove Hosokawa Yoriyuki from the kanrei post, and he returned as kanrei. While aiding Yoshimitsu, the system of three kanrei houses—Shiba, Hosokawa, Hatakeyama—took shape.
He also became shugo of Shinano, greatly widening Shiba provinces. As shugo daimyo he balanced lands and bakufu politics.
As the Northern and Southern Courts reunited under Yoshimitsu, he backed bakufu politics as kanrei. He balanced shugo interests and sought stronger, stabler shogunal power. He prized practice and talk over show.
He took vows as Dosho. That year he was also involved in dismissing Kyushu tandai Imagawa Ryoshun, who later voiced anger at Yoshimasa in the Nantaiheiki. As a cabinet core he backed Yoshimitsu's control of daimyo in practice.
When Yoshimitsu died suddenly, he backed Yoshimochi as shogun and declined a retired-emperor title for Yoshimitsu. He also reviewed the tally trade and helped steer Yoshimochi's government away from the father's showy politics.
For diplomatic business he briefly became kanrei again, then passed the post to his grandson Yoshiatsu. It was a move to tighten Shiba hold on bakufu politics, but his death the next year cut the plan short.
In Oei 17 he died of illness at sixty-one. People are said to have mourned him as a pillar of the warrior houses of his day. Backing Yoshimitsu and Yoshimochi as leading kanrei, his life marks a stable age of the Muromachi bakufu.
Ashikaga YoshimochiHosokawa Yoriyuki
Hosokawa YoriyukiAshikaga YoshiakiraKan'amiAshikaga MotoujiAshikaga YoshimitsuZeamiShō HashiMansai
People of the Muromachi period ・ People by period
Based on facts found in textbooks and biographies. Uncertain points are marked as such.