To simplify the structure of a partitioning member by integratedly forming a thick- walled part to a peripheral part of an elastic rubber membrane, covering and fixing a peripheral part of the partitioning member to the thick-walled part, and forming an orifice passage between the thick-walled part and the partitioning member in the circumferential direction.

An annular thick-walled part 54 which is extended along an annular plate 42 and projected on its upper surface side is integrated with an outer peripheral part of an elastic rubber membrane 40. The thick-walled part 54 is provided with a cylindrical circumferential wall part 56, a recessed groove 58 is formed on its outer peripheral side in the circumferential direction, and the thick-walled part 54 is provided with one bulkhead part on one part of the circumference of the recessed groove 58. A fitting groove 62 is formed in a partition plate 38 in the circumferential direction at the position corresponding to the circumferential wall 56, an upper end part of the circumferential wall part 56 is fitted therein, an orifice passage 52 is formed in the circumferential direction between the circumferential wall part 56 and the partition plate 38, and one end part in its circumferential direction is communicated with a pressure receiving chamber 48 through a communication hole 66 in the partition plate 38, and the other end part is communicated with a balancing chamber 50 through a communication hole in the circumferential wall part 56. The press-molded partition plate can be adopted, and the orifice passage can be formed with less number of part items in a simple structure.