Abstract: A method of making a hermetically sealed container is disclosed. In the method, a water vapor (40) is blown into a container body (1) that has been placed with a product such as solid foods or the like leaving a space portion (3). Immediately thereafter or immediately after an inert gas (51) has been blown into the container body, the container body is hermetically sealed. The container has a relatively low negative internal pressure which is controllable with a small range of variation. The water vapor (40) is generated by blowing a non-condensable gas such as air, nitrogen gas or the like at a constant flow rate into a water (13) which is controlled to a constant temperature. When the inert gas (51) is blown, only the surface and its vicinity of the product (4) is heated by blowing the water vapor (40).