PURPOSE: To reduce the extent of low frequency large amplitude of vibration as well as to check the worsening of high frequency vibration by installing a stopper means, controlling a low frequency vibration, in a nearby part where low frequency amplitude in an intermediate part of a power plant frame becomes maximized.
CONSTITUTION: A power unit 4 inclusive of an engine 1 is mounted on a front cross-member via an elastic member. On the other hand, a differential 5 is mounted on a rear cross-member, and an interval between both these elements 4 and 5 is connected by a power plant frame 6 which is made up of joining an inner frame 22 to the inner surface of a section U-shaped outer frame 21 opened crosswise, and is installed in a tunnel part 41 of a car body. In this case, a member 50 is installed in this tunnel part 41 in the car width direction, and both the ends 51 are clamped to a car body. In addition, a through hole 52, where the member 50 is pierced through, is formed in the power plant frame 6. In this connection, the member 50 is installed in a part where the amplitude of low frequency vibration in the power plant frame 6 is the largest.