He enjoyed the deep confidence of Emperor Shomu and, together with KIBI no Makibi, was promoted for his contribution to the administration of TACHIBANA no Moroe, but people were critical of his personality, and in 740, Fujiwara no Hirotsugu mobilized troops in Kyushu for the ouster of Genbo, albeit unsuccessfully (the Rebellion of Fujiwara no Hirotsugu).
聖武天皇の信頼も篤く、吉備真備とともに橘諸兄政権の担い手として出世したが、人格に対して人々の批判も強く、失敗したものの740年（天平12年）には藤原広嗣が玄昉を排除しようと九州で兵を起こした（藤原広嗣の乱）。