Damper

A damper capable of satisfactorily absorbing any torsional vibration occurring on a crank shaft even in the use at extremely low temperatures. The crank shaft of engine has a hub capable of joint rotation therewith fixed thereto, and an inertial mass disposed outside the hub is coupled with the hub by means of a rubbery elastomer. The damper exhibits a ratio of characteristic frequency along the torsional direction at -30°C (F-30) to characteristic frequency along the torsional direction at 60°C (F60), F-30/F60, of 1.5 or below, while the rubbery elastomer exhibits a ratio of storage modulus at -30°C (E'-30) to storage modulus at 60°C (E'60), E'-30/E'60, of 3.0 or below. The rubbery elastomer comprises an ethylene-propylene copolymer rubber of 51% or less ethylene weight ratio as a main component and, mixed with 100 pts.wt. thereof, 5 to 30 pts.wt. of an aliphatic dibasic acid ester plasticizer.