To provide a cooking container for a microwave oven which is capable of effectively utilizing a higher internal steam pressure, when cooked in a microwave oven, by making the container of a structure such that while part of the steam is discharged outside, even if the steam pressure is caused to further rise, a lid body is made into a structure difficult to be removed.

The cooking container 10a for a microwave oven comprises a main container body 20a and a lid 30a. A corrugated projection 60 which faces inwardly is formed on an upper inside portion of the main container body 20a and a corrugated projection 70 which faces outwardly is formed on a folded-back portion 80 formed at a lower portion of the lid 30a. The main container body 20a has a stepped portion 24 and the lid 30a has a bottom portion 82 at the folded-back portion 80, so that when the bottom portion 82 abuts against the stepped portion 24, the two corrugated projections engage with each other, with one being located above the other. The lid 30a is movable slightly upward. When the upward movement occurs, steam is discharged from a steam discharge groove 50 which is formed on the upper inside portion of the main container body 20a and through which the inside and outside of the container communicate with each other.