To provide a lock-up damper device which is stored in a torque converter for reducing impact torque while suppressing the occurrence of judder vibration.

A damping mechanism 13 is mounted over between a piston 4 and a turbine hub 10 on which a turbine runner 2 is mounted. The damping mechanism 13 consists of a one-way clutch 11 which idles when damper springs 9, 9 of the lock-up damper device 5 are compressed and deformed, and a sliding member 12 which generates sliding friction when the damper springs 9, 9 elongate.