To improve heat resistance of a friction member of a lock-up clutch used in a torque converter.

This drawing is an enlarged cross sectional view of a main part of the lock-up clutch, and 21 and 5 indicate a front cover and a clutch piston, respectively. The friction member is divided into an outside diameter side friction member 71 for performing slip control for making μ-ν characteristic a positive gradient to suppress occurrence of judder and an inside diameter side friction member 72 having large coefficient of static friction and large torque capacity when engaging the clutch, and the outside diameter side friction member 71 and the inside diameter side friction member 72 are stuck to a piston 5 and a front cover 21, respectively. Consequently, heat of the outside diameter side friction member 71 having a large calorific value is transmitted to a front cover 21 side having large heat capacity and high heat radiation effect, thereby increasing heat resistance of the outside diameter side friction member.