To prevent the number of parts from being increased due to a trigger plate in a damper with trigger plate, a damper which is formed by interposing a sleeve and an elastic body between a hub fitted to a rotating shaft and an annular mass body disposed at the outer peripheral side of the hub, is characterized in that a magnetized trigger plate is integrally fitted, at specified pitch in the circular direction, to one end part of the sleeve, and the sleeve is fitted to the outer peripheral side of the hub or the inner peripheral side of the annular mass body.