When Masakado started to call himself 'the new emperor,' Masatake was appointed to Izu no kami; however, his power declined at a stretch after Masakado died in the battle with TAIRA no Sadamori and FUJIWARA no Hidesato on March 30, 940, and eventually, Masatake was also killed.
将門が「新皇」を僭称すると伊豆守に任ぜられるが、天慶3年（940年）2月14日、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、将武も討たれた。