To provide a repeatedly usable container for microwave cooking steaming a food while preventing a foodstuff such as soup from boiling over, preventing detachment of a lid and bumping by adjusting the pressure inside the container.

The container 10A for microwave cooking includes a container body 1a, the lid 2a, and a cap 3. When a foodstuff is loaded in the container 10A for microwave cooking and put on a microwave oven, steam is discharged from a gap between an annular recess 21 and a flange 31 of the cap 3 or from a steam outlet groove 27 to the outside. When heating is finished, the cap 3 is automatically fitted to the lid 2a to seal the inside of the container 10A. In this way, the food can be steamed while preventing the lid 2a from being detached from the container body 1a. The container body 1a may be made of a material the same as of that of a glass, ceramic, or hard plastic cup sold in the market, and a special treatment is not necessary to fit the container body with the lid.