To solve the problem of a conventional high-pressure supply apparatus having a structure as a hard dual structure or a substantially one-layered flexible structure made of a thick EVA resin or the like with pressure resistance and air-impermeability so as to satisfy a need to switch the internal pressure alternatively between high and low pressures, the problem that the apparatus is heavy, difficult to fold and too bulky to carry to use at arbitrary places because certain strength and thickness are necessary for the structure of the conventional apparatus.

A high-pressure gas supply apparatus has a flexible and foldable outer bag body 1 having air-permeability and pressure resistance against high-pressure gas and a flexible and a foldable inner bag body 10 having air-impermeability against high-pressure gas. The bag bodies have a pressurizing mechanism for supplying high-pressure gas to the bag bodies when the inner bag body is covered with the outer bag body. Under a pressurized condition, the shape of the inner bag body is maintained by the outer bag body.