An object of the present invention is to reproduce vehicle behavioral frequencies during a vehicle test that are close to those on a road. Vehicle restraining devices 1 restrain a vehicle 3 provided on a chassis dynamometer 2 and are each provided with a first attachment member 4, a support post unit 5, a second attachment member 6 and a buffer unit 7. The first attachment members 4 are attached to right and left front end portions and rear end portions of the vehicle 3. The second attachment members 6 are attached to the support post units 5. The buffer units 7 are provided between the first attachment members 4 and the second attachment members 6. Further, the buffer units 7 are filled with air and can be compressed freely.