To provide a lock-up device which suppresses an output-side rotation fluctuation in a wide rotational speed range without growing in size.

A dynamic damper device includes: a pair of plates 21 and 22 into which torque is input and which can be connected to a turbine hub; a hub flange 23; an inertia member 24 which is fixed to the hub flange 23; a torsion spring 25; and a hysteresis torque generation mechanism 26. The hub flange 23 can be rotated relatively to the plates 21 and 22, between the pair of plates 21 and 22. The torsion spring 25 elastically connects the pair of plates 21 and 22 and the hub flange 23 together. The hysteresis torque generation mechanism 26, which is arranged on the inner peripheral side of the hub flange 23, between the pair of plates 21 and 22, generates variable hysteresis torque between both the plates 21 and 22 and the hub flange 23.