A damper device is provided with a first rotating body, a second rotating body, a coil spring and a spring seat. The coil spring is interposed in a circumferential direction between the first and second rotating bodies. The resin spring seat includes a metallic core member inside. The resin spring seat has a seat portion and an overhang portion. The metallic core member has includes a metallic core seat part with a metallic core exposed portion. The metallic core seat part is provided along the spring seating surface in the seat portion of the spring seats. The metallic core exposed portion is exposed so as to be capable of abutting the coil springs. The metallic core exposed portion is provided on a portion of the spring seating surface which slides against the coil springs.

A flywheel assembly includes a first rotary member, a second rotary member, a first coil spring, a second coil spring, an intermediate plate, a first stopper mechanism and a first contact relief member. The first coil spring is configured to be compressed between the first rotary member and the second rotary member. The second coil spring is configured to be compressed between the first rotary member and the second rotary member and has a stiffness greater than a stiffness of the first coil spring. The intermediate member is engaged with the first coil spring and the second coil spring and couples the first coil spring and the second coil spring in series. The first stopper mechanism is configured to deactivate the first coil spring. The first contact relief member is movably disposed inside the first coil spring and is capable of relieving the contact in the first stopper mechanism during activation of the first coil spring.

A damper device includes a first rotary member, a second rotary member, a plurality of coil springs, an intermediate member and a positioning structure. The first rotary member is a member into which a power of an engine is inputted. The second rotary member is disposed to be rotatable with respect to the first rotary member. The plurality of coil springs are configured to be compressed between the first rotary member and the second rotary member. The intermediate member is engaged with the plurality of coil springs and couples the plurality of coil springs together. The positioning structure radially positions the intermediate member with respect to at least either of the first rotary member and the second rotary member on an inner peripheral side.

In a method of assembling a damper device, a first support portion of a first rotor and a first accommodation portion of a second rotor are overlapped to eliminate an axial offset between them. A first elastic member is placed in the first support portion and the first accommodation portion. A second support portion of the first rotor and a second accommodation portion of the second rotor are overlapped to eliminate an axial offset between them by simultaneously compressing the first elastic member and rotating the second rotor relative to the first rotor to a first-side in a rotational direction. A second elastic member is placed in the second support portion and the second accommodation portion. Simultaneously, the second elastic member is compressed and the second rotor is rotated relative to the first rotor to a second-side in the rotational direction by angle corresponding to the offset between the first support portion and the first accommodation portion.