A lock-up clutch of a torque converter includes an annular clutch outer mounted in a side cover, a clutch inner connected to a turbine impeller, a driving friction plate axially movably connected to the clutch outer, first and second follower friction plates connected to the clutch inner for movement toward and away from each other with the driving friction plate interposed therebetween, an inner chamber defined between the first and second follower friction plates, and an outer chamber faced by outer sides of the first and second follower friction plates. When the inside of the outer chamber is put at a pressure higher than that in the inner chamber, the follower friction plates are brought into pressure contact with the driving friction plate, and an urging force on the follower friction plates is not applied to the side cover.