Use of an anti-vibration device in a vehicle, with - the vehicle comprising: - a vehicle body and - a variable compression ratio engine mounted to the vehicle body, and - the anti-vibration device comprising: - a rod body having a first elastic connecting part at one end and a second elastic connecting part at another end, with the second elastic connecting part being connected to a variable compression ratio engine , with the first elastic connecting part being connected to the vehicle body; - an inertial mass supported by the rod body ; - an actuator configured to reciprocate the inertial mass in an axial direction (C) of the rod body ; and - a control unit configured to control the actuator so that the inertial mass receives force in accordance with a displacement speed of the rod body in the axial direction (C), wherein - the variable compression ratio engine is provided with a multi-link mechanism between a piston and a crankshaft , - the multi-link mechanism includes an upper link , a lower link and a control link , - the anti-vibration device is attached between an upper part of the variable compression ratio engine and the vehicle body, - the rod body has a rigid body resonance frequency lower than a resonant frequency of bending and twisting of the variable compression ratio engine , and - each of vibration eigen frequencies of the first elastic connecting part and the second elastic connecting part about an axis connecting two support points (P1, P2) of the variable compression ratio engine is within a range of 100±10 Hz. - the vehicle comprising: - a vehicle body and - a variable compression ratio engine mounted to the vehicle body, and - a vehicle body and - a variable compression ratio engine mounted to the vehicle body, and - the anti-vibration device comprising: - a rod body having a first elastic connecting part at one end and a second elastic connecting part at another end, with the second elastic connecting part being connected to a variable compression ratio engine , with the first elastic connecting part being connected to the vehicle body; - an inertial mass supported by the rod body ; - an actuator configured to reciprocate the inertial mass in an axial direction (C) of the rod body ; and - a control unit configured to control the actuator so that the inertial mass receives force in accordance with a displacement speed of the rod body in the axial direction (C), - a rod body having a first elastic connecting part at one end and a second elastic connecting part at another end, with the second elastic connecting part being connected to a variable compression ratio engine , with the first elastic connecting part being connected to the vehicle body; - an inertial mass supported by the rod body ; - an actuator configured to reciprocate the inertial mass in an axial direction (C) of the rod body ; and - a control unit configured to control the actuator so that the inertial mass receives force in accordance with a displacement speed of the rod body in the axial direction (C), - the variable compression ratio engine is provided with a multi-link mechanism between a piston and a crankshaft , - the multi-link mechanism includes an upper link , a lower link and a control link , - the anti-vibration device is attached between an upper part of the variable compression ratio engine and the vehicle body, - the rod body has a rigid body resonance frequency lower than a resonant frequency of bending and twisting of the variable compression ratio engine , and - each of vibration eigen frequencies of the first elastic connecting part and the second elastic connecting part about an axis connecting two support points (P1, P2) of the variable compression ratio engine is within a range of 100±10 Hz. <EOS>