In a metal bellows accumulator, a metallic bellows unit is disposed within a pressure space defined in a main shell, and one end of the metallic bellows unit is fixedly secured to one end wall of the main shell. The metallic bellows unit sections the pressure space into an outer chamber serving as a gas chamber in which a pressurized gas is enclosed, and an inner chamber serving as a liquid chamber communicating with a liquid port formed in the end wall of the main shell. A stopper (auxiliary shell) for limiting collapsing movement of the metallic bellows unit is disposed within the liquid chamber and has a communication passage hole. The liquid port always communicates with a liquid chamber to which an inner circumferential surface of a bellows portion of the metallic bellows unit is exposed via the communication passage hole.