The object of the invention is to provide a lockup device that can improve a fuel efficiency of a vehicle. The 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 coupled to a turbine (4) such that it can rotate as an integral unit with the turbine (4). The first coil spring (65) elastically couples the piston (61) to the output plate (63) in a rotational direction. The inertia member (64) is provided such that it can rotate relative to the output member (63). The second coil spring (66) elastically couples the inertia member (64) to the output plate (63) in a rotational direction.