To provide a vibration damping device improving vibration damping performance.

A lockup device 6 has: a piston 61; an output plate 63; a first coil spring 65; an inertia member 64; and a second coil spring 66. The output plate 63 is connected to a turbine so as to be rotatable integrally with the turbine. The first coil spring 65 elastically couples the piston 61 to the output plate 63 in the rotational direction. The inertia member 64 is rotatably provided relative to the output plate 63. The second coil spring 66 elastically couples the inertia member 64 to the output plate 63 in the rotational direction, and both constitute a dynamic damper 82, wherein a lock mechanism is provided which restricts the action of the dynamic damper 82 within a predetermined rotational speed range.