As for his year of birth, "Mizu Kagami (The Water Mirror)" and "Ichidai Yoki" (summary chronicle of each reign) reported that he was born in 761, but in this case, Imperial Princess Inoe gave birth to him when she was 45 years old, this is questionable, so that many historians believe that the correct year of birth is 751.
生年については『水鏡』・『一代要記』の年齢記事によれば天平宝字5年となるが、この場合母親の井上内親王が45歳の時の子となってしまい年齢が不自然であるとして、正しい生年を天平勝宝3年（751年）とする歴史学者が多い。