The credibility of this document has been a controversial issue in the society of Japanese history that majority of them viewed as false; however, an old document that was found in the house of a wealthy farmer, the Nagatomi family (the birthplace of Morinosuke KAJIMA who was the chairman of Kajima Corporation and the former advisor of the Kusunoki family council) in Shinzaike, Ibokawa-cho in Ibo-gun, Hyogo Prefecture and it was revealed that this geneology recorded in this manuscrit during the late Edo Period was actually copied from an old document.
上嶋家文書の真偽をめぐって学界では意見がわかれ、概ね否定的見解が主流であったが、後にその記載内容を裏書きする古文書が兵庫県揖保郡揖保川町新在家の豪農であった永富家（元楠木同族会顧問　鹿島建設株式会社会長鹿島守之助の生家）から発見され、この系図は江戸後期の写しであっても、古本を書写したものであることが証明された。