According to Shoku Nihongi (Chronicle of Japan Continued), KIBI no Makibi, who had joined the party of Kento-shi (Japanese envoy to Tang Dynasty China) twice to study abroad and then had become a high official in Dazaifu Seicho (local government office in the Kyushu region), started to construct a castle under the order of Emperor Koken in July, 756.
続日本紀によると、遣唐使一行に加わること2度留学し、その後大宰府政庁の高官となった吉備真備が、孝謙天皇の命により天平勝宝8年（756年）6月築城に着手。