To provide an accumulator including an emergency safety mechanism capable of being operated at a pressure lower than that when circumferentially locally providing a rupture disc on a peripheral surface of a stay, and in addition, to provide an accumulator capable of achieving production of the stay only by press working.

An accumulator includes an emergency safety mechanism releasing internal pressure of a housing to a side of an oil port so that the housing is not exploded by the internal pressure of the housing, increased in case of emergency such as fire occurrence. The emergency safety mechanism has a tapered portion at a corner between a cylindrical portion of the stay and an end surface portion thereof. The tapered portion is buckled at its root portion in the case of emergency. When the tapered portion is buckled, a bellows cap or a member to be held and the end surface portion of the stay are separated from each other, and also a pressure releasing flow passage is formed between the bellows cap or the member to be held and the tapered portion.