A first flywheel assembly a first flywheel, a second flywheel, a first spring set, a first spring seat, and a second spring set. The first spring set is arranged between the first flywheel and the second flywheel in a pre-compressed state. The first spring seat is a member that supports an end portion of the first spring set and is pushed in a radially outward direction against the first flywheel. The second spring set is a member having a lower stiffness than a stiffness of the first spring set and is arranged between the second flywheel and the first spring set in a pre-compressed state such that it acts in series with the first spring set.