When Nagayoshi died in July 1564, he succeeded to the Miyoshi family supported by Miyoshi Sanninshu (Miyoshi Triumvirate) and became the family head of the Miyoshi family (according to another theory, Nagayoshi transferred the headship of the family and retired while he was alive).
永禄7年（1564年）7月に長慶が死去すると、三好三人衆の支持を受けて家督を継ぎ、三好家の当主となる（一説に、長慶は存命中の6月に家督を譲って隠居していたとされる）。