Provided is a safety-device-fitted electrochemical device such that sufficient sealing ability can be secured in a case enclosing the main unit part of the electrochemical device, and such that de-gassing can be performed when the internal pressure of the case rises so as to prevent an explosion of the case due to the increase in the internal pressure. In this safety-device-fitted electrochemical device, the constitution is such that, a movable plate (4) provided with a perforating protrusion (5) is disposed between the case (2) and the main unit part (3), and when the case (2) expands and deforms due to an increase in the internal pressure caused by a gas generated inside the case, the perforating protrusion(5) of the movable plate (4) moves toward the case (2) in conjunction with this expansion and deformation.