He established his headquarters in Miuraso Kinugasa in Sagami Province (present Yokosuka City, Kanagawa Prefecture), called himself Miura clan and also used the name of Miura no suke which was a hereditary official position and he attended to state affairs between 1124 and 1126, during which he extended his influence to the entire Miura Peninsula.
相模国三浦荘衣笠（現神奈川県横須賀市）を本拠として三浦氏を称し、世襲の官である三浦介を号して天治年間（1124年-1126年）国務に参画し、三浦半島一帯に勢力を扶植する。