His family line was a branch family of the Ogasawara clandescended from the Kai-Genji (Minamoto clan), collateral line of Kawachi-Genji which was a family of the Seiwa-Genji.
家系は清和源氏の一家系・河内源氏の傍系・甲斐源氏の流れを汲む小笠原氏の庶家にあたる。