Provided is a container that allows a portion where detachment starts to be fixed at a specified position in a more reliable manner, thus allowing contents to be discharged in a direction expected by a user, allowing eventually reduction in the amount of contents to remain in the container in the end. The container includes a container body holding contents therein and a lid member, the container body and the lid member being sealed by an annular seal portion formed along a flanged face of the opening. There is provided a detaching seal portion which is detached in response to increase of pressure inside the container body associated with deformation of the container body. The detaching seal portion includes a reverse-oriented annular seal portion which occupies a part of a width of the flanged face and which projects toward a radial inner side of the opening.