Secondary vibration generated accompanying reciprocation of a piston (21) of a multi-link variable compression ratio engine (E) can be eliminated effectively, even when the direction of the secondary vibration is inclined relative to a cylinder axis (L1), by inclining the direction (shown by arrow) of an excitation force generated by a secondary balancer system (43) so that it coincides with the direction of the secondary vibration. The secondary balancer system (43) is formed by supporting balancer weights (44a, 45a) on a pair of balancer shafts (44, 45) rotating in directions opposite to each other, and by displacing the phases of these balancer weights (44a, 45a) the direction of the excitation force generated can be inclined so as to coincide with the direction of secondary vibration of the engine (E).