PURPOSE: To reduce the power loss of a plate by making the cross-sectional area of oil grooves of an annular frictional member fitted closely on a core plate larger at the outer periphery side and smaller at the inner periphery side of it.

CONSTITUTION: A drive plate 11 as wet type frictional engagement plate comprises a core plate 12 and a facing 13 as frictional member. Oil grooves 14 and air grooves 17 are provided on the facing 13, and the cross-sectional area of the oil grooves 14 at the outer periphery edge 16 of the facing 13 is larger than that at the inner periphery edge 15 of it. A lubricating oil is moved from the internal side of the oil groove to the external side of it by centrifugal force, and it sucks air due to negative pressure generated by increased cross-sectional area. Thus the viscous resistance of the lubricating oil is reduced and, accordingly, the power loss is reduced.