Pressure relief container for food to be heated and box having said container

A container for food to be heated, comprising:

• a bottom surface;
• a side wall connected to the bottom surface, wherein the side wall and the bottom surface together form an accommodation space in communication with outside of the container;
• a peripheral portion connected to the side wall and surrounding the accommodation space, wherein the peripheral portion has a peripheral plane, an inner edge, and an outer edge;
• the inner edge and the outer edge are borderlines of the peripheral portion and are respectively connected to the peripheral plane, the inner edge is on a side of the peripheral plane nearer the accommodation space, and the outer edge is on a side of the peripheral plane farther from the accommodation space;
• a convex strip, protruding from the peripheral plane, wherein an extension direction of the convex strip is parallel to an extension direction of the peripheral plane, the convex strip has a top surface, the top surface being parallel to the peripheral plane;
• and
• a groove on the peripheral plane, wherein the groove is in contact with the inner edge or the outer edge, and the groove at least partially overlaps the convex strip, so that the groove, the peripheral plane, and the top surface of the convex strip form a stepped structure, wherein
• when a sealing film is attached to the stepped structure to enclose the accommodation space, the sealing film covers the top surface and is attached to a portion of the peripheral plane.