PURPOSE: To heighten safety of a pressure vessel as well as to reduce weight of the pressure vessel by arranging an outer shell having permeability to inside fluid and a liner which seals up the inside fluid and has a destructible part to be destroyed partially under a prescribed pressure.

CONSTITUTION: When excessive internal pressure rise occurs and its value becomes higher than a prescribed value, a partial destructible part 6 arranged in a liner 3 is ruptured, and inside fluid is leaked out from there. This leaked inside fluid has penetrability, and leaks outside through an outer shell 2 being as a main strength member, so that pressure in a pressure vessel 1 is lowered. Thereby, the whole vessel body can be prevented from being destroyed explosively.