The causes of the downfall of the Oshu Fujiwara clan were that the Minamoto clan strengthened its power through the downfall of the Taira clan, and that it failed to maintain its neutrality because Yoshitune, who had had a close relation with the clan, became opposed to Yoritomo.
平家滅亡により源氏の勢力が強くなった事、奥州に深く関わっていた義経が頼朝と対立した事などにより中立を維持できなくなった事が滅亡の原因となった。