PURPOSE: To improve vibration isolation performance for a car body and accurately control deflection of an engine by forming a stopper member movable to a mount rubber.

CONSTITUTION: When low speed operation sphere is detected and its signal is inputted to a control device 14, oil pressure introduced in a cylinder 11a of an actuator 11 from an oil pressure source 13 turns high, and puts a piston 11b and a piston rod 11c in forward movement against the spring tension of a spring 18, and further puts a head 10 of a stopper member 9 in close vicinity to a mount rubber 3 of an engine mount 2A. This greatly reduces a shock at the time of collision of the mount rubber member 3 with the head 10 of the stopper member 9, and a vibration at the time of collision is not transmitted to the car body. On the other hand, although the head 10 is separated from the mount rubber 3 in a high speed operation sphere, vibration isolation can be performed sufficiently.