PURPOSE: To prevent surface vibration resonance by coupling a damper mass to a flywheel, swingably in the directions of surface vibration through the intermediary of pins at symmetrical positions in the maximum rigid direction of a crank shaft corresponding to an engine cylinder nearest to the flywheel.

CONSTITUTION: An annular damper mass 11 is coaxially disposed between a flywheel 5 and a damper support member 8 through the intermediary of a damper spring 10. This damper mass 11 is coupled to the support member 8, swingably in the direction of surface vibration, by solid pins 12, 12 which are secured to the support member 8 in the maximum rigid direction of a crankshaft 3 corresponding to an engine cylinder nearest to the flywheel 5, that is, the direction orthogonal to the crank arm low rigid direction, and at positions symmetrical with each other with respect to the center axis of the flywheel 5. Thus, the center axis of the damper mass 11 may be precisely aligned with that of the flywheel when it is mounted, thereby it is possible to satisfactorily prevent surface vibration resonance of the flywheel.