An engine includes a crank mechanism and a balancer mechanism that inhibits vibrations caused by the crank mechanism. An instantaneous center of rotation of an engine is arranged in the neighborhood of a predetermined target position by adjusting an acceleration caused by a translational force generated by a primary inertial force of the crank mechanism and an inertial force of the balancer mechanism and an acceleration caused by a couple of forces generated by the primary inertial force of the crank mechanism and the inertial force of the balancer mechanism.