In February, 940, when Masakado was defeated and killed in the war against TAIRA no Sadamori and FUJIWARA no Hidesato, his power instantly collapsed, and it is said that Masahira hid himself in the Jomine Mountain in Chichibu County, Saitama Prefecture, and his grave is in Enpuku-ji Temple in Minano-machi Town in the same area.
天慶3年（940年）2月、将門が平貞盛・藤原秀郷らとの戦いによって敗死すると勢力は一気に瓦解し、将平は追捕を免れようと埼玉県秩父郡の城峯山中に潜伏したと伝えられ、同地の皆野町にある円福寺に墓が祀られている。