To prevent a container and a cover from being deformed or broken and also the contents from leaking out when the food contents are sterilized in an extra- high pressure condition, even if the container is a rigid plastic container with a cover fastened by a metallic winding material, by providing a recessed thin part having a specified volume at the almost center of the container bottom.

A thin part 3 recessed to the inside of a container is formed at the almost center of the bottom 2 of the food container 1. The upper edge of the peripheral side faces 4 of the container is opened and food is contained in the inside and a cover 5 fastened by a metallic winding material is fitted to the upper edge of the peripheral side faces. In this time, the volume V of the recessed thin part 3 is designed to be within the following formula; Vr.R/100≤V≤(Vr.R/100)+HS, where Vr is charged volume (volume cc) of the food contents, R is contraction ratio (%) of water corresponding to the prceessing pressure, HS is head space volume (cc) in the container. When the thin part 3 is compressed and deformed and food is contained and sterilized in an extra-high pressure condition, the voluminal change due to the shrinkage is absorbed by the deformation of the thin part 3 and hence, the deformation and breakage of the container is prevented.