It was said he was furious that he was demoted from nobility to a subject in his later years, but there was a record of FUJIWARA no Tadahira's diary, who was Sessho Daijo daijin (Regent and the Grand Minister) at that time, "Teishinkoki" (diary of FUJIWARA no Tadahira) dated March 31, it said 'MINAMOTO no Tsunemoto reported about Musashi.'
晩年、経基は臣籍降下を命じられたことに憤慨していたというが、同時代の摂政太政大臣・藤原忠平の日記『貞信公記』の天慶2年(939年)3月3日付に「源経基、武蔵の事を告げ言う。」と記されているのもある。