A damper device includes a stator, a rotor, and a viscous fluid imparting a resistance to a rotation or a relative rotation of the rotor, and forms a braking force by the resistance. In the rotor, an annular seal portion made of soft synthetic resin is provided by integral molding. The stator includes an annular space in which the viscous fluid is filled, and a main member portion of the rotor is housed in the annular space. The annular seal portion comprises an outside annular portion provided in an outer circumferential portion of the rotor; an inside annular portion provided in an inner circumferential portion of the rotor; and a connection portion therebetween.