Baekje Gunchang or Military Warehouse is thought to have been used to store food for the army or serve as a place of refuge. It is located in the eastern part of Busosanseong Fortress. The warehouse building was large and shaped like a square with an empty space in the middle. The name "Baekje Gunchang" was given since the site revealed the situation at the time of the collapse of Baekje.

However, presumably, it had been used continuously from the Baekje Period until the Joseon Dynasty. In 1915, Burnt grains dating back to the Joseon Dynasty were found. Also, the excavation was carried out again in 1981 and 1982 and the size of the warehouse site was discovered in detail. Moreover, some pillar holes, lotus pattern pieces, and the early Joseon Dynasty warehouses were found. Currently, the excavation work is still being done around the military warehouse site.