To prevent a container from being eroded by caustic soda when it is exposed thereto in the washing process and make applicable an existing washing process as it is, by coating both inside and outside faces of the container body made of an aluminum alloy with fluororesin.

Both inside and outside faces of an aluminum alloy container body 1 are coated with fluororesin 7 typified by tetrafluoroethylene. In this way, when the container is exposed to caustic soda, the aluminum of the container body 1 is prevented from being eroded and hence, a beer barrel container made of aluminum alloy can be used in the washing process in existing equipment. The fluororesin coating is independently applied to both inside and outside faces of the upper body 4, the opening 5, and the lower body 6 respectively and then these are integrally combined or after the upper body 4 and the opening 5 have been integrally formed or after the three of the upper body, the opening, and the lower body have been integrally formed, the coating is applied to the inside face and the outside face.