The Ministry of War or Military Ministry[1] (兵部省, Hyōbu-shō), sometimes called Tsuwamono no Tsukasa, was a division of the eighth century Japanese government of the Imperial Court in Kyoto,[2] instituted in the Asuka period and formalized during the Heian period.

The highest-ranking official or head of the military (兵部卿,, Hyōbu-kyō) was ordinarily a son or a close relative of the Emperor.

This important court officer was responsible for directing all military matters; and after the beginning in the late 12th century, this military man would have been empowered to work with the shogunate on the emperor's behalf.

[3] The ambit of the Ministry's activities encompasses, for example: The ministry was established as part of the Taika Reforms and Ritsuryō laws which were initiated in the Asuka period and formalized during the Heian period.

The Asuka-, Nara- and Heian-period Imperial court hierarchy encompassed a ministry dealing with military affairs.