In order to further improve driving stability, a dumper 10 mounted in a vehicle 14 in which a drive unit 11 having an engine 11a and a drive shaft 12 having tires 13 connected to respective end portions in the axial direction thereof, to which drive shaft torque is transferred from the engine 11a, are provided in a vehicle body frame 2, comprises: a connection part 16 for connecting the drive unit 11 with the vehicle body frame; a detection means 17 for detecting variation of torque transferred from the drive unit 11 to the drive shaft 12; and a controller 18 for controlling at least roll vibration of vibration behaviors of the drive unit 11 by operating the connection part 16 on the basis of a detection signal from the detection means 17.