To provide a fluid sealing type damping device having a novel structure effective for attaining high reliability on the closing-opening of a valve member and achieving the high flow action of the fluid through an orifice flow passage to realize a desired stable damping effect.

A short-circuit flow passage 90 is formed on the outer peripheral side of a movable rubber diaphragm 68 of a partitioning member 32, separately from the orifice flow passage 50. An elastic-wall valve 94 is formed integrally with the movable rubber diaphragm 68, and is protruded from the outer peripheral surface of the movable rubber diaphragm 68. A valve member accepting portion 92 having the elastic-wall valve 94 disposed therein is formed in the short-circuit flow passage 90. The elastic-wall valve 94 is pushed with an elastically fastening margin against a valve seat 82 formed in the valve member accepting portion 92, so that the short-circuit flow passage 90 is kept in the isolation state. The short-circuit flow passage 90 is set into the communication state by the elastic deformation of the elastic-wall valve 94 based on the difference between a negative pressure generated in a pressure chamber 42 and the pressure in a balancing chamber 44.