To provide a substantially sealed container by providing a structure of a plurality of stages where a plurality of container bodies are stacked to communicate with each other, and providing a single vent valve on a lid body of the container body of the upper stage to simultaneously seal the upper stage container body and the lower stage container body stacked in a plurality of stages for preservation and portable use.

A plurality of container bodies 1A and 1B are stacked in a plurality of upper and lower stages through a sealing plate 26 so that an opening part 5 of the lower stage container body 1B by a bottom plate of the container body 1A. In addition, a vent valve 3 to be opened/closed by the internal pressure is provided on a top plate 10 of a lid body 2 to be sealed to an upper end part of a circumferential side plate 8 of the upper stage container body 1A through a packing 17. A vent 11 to communicate with a vent 39 in the sealing plate 26 is pierced in an end part of the bottom plate 4 between a partition plate 36 of an inner container 37 to be placed in the container body A1 and the side plate 8. The stacked sealed containers are tightened by an expandable band 40, and heated in a microwave oven. Then, the air inside is emitted from the vent valve 3, and when the inside temperature is dropped, the vent valve is closed to keep the sealed condition.