The invention provides a metal bellows type accumulator having an outer shell provided in its one end with a pressure introducing passage in an opening manner, and a metal bellows repeatedly formed peak portions directed to an outer side in a radial direction and trough portions directed to an inner side, capable of expanding and contracting in an axial direction and separating an inner chamber of the outer shell into a pressure introducing chamber communicated with the pressure introducing passage and a gas chamber charged with cushion gas. A tubular portion is provided at a position where an amplitude of vibration in a radial direction becomes maximum in the metal bellows, has a greater diameter than a maximum diameter portion of each of the peak portions and is in contactable with an inner peripheral surface of the outer shell at a predetermined width in the axial direction.