To provide a lubricating structure for a frictional engagement device which automatically adjust quantity of lubricating oil according to operation conditions such as rotation speed and rotation direction of the frictional engagement device to secure sufficient supply quantity when lubricating oil is required and to increase power transmission efficiency by reducing drag torque by reducing supply quantity when lubricating oil is not required, and of which number of components and cost are not different from former structures.

This lubricating structure for the frictional engagement device includes lubricating oil holes which pass through a drum shape rotary member rotatably supported by a housing from an inner circumference side to an outer circumference side and supply frictional engagement elements with lubricating oil. In the lubricating structure, a plurality of grooves (spline grooves 42) are formed in an axial line direction from an inner diameter side toward an outer diameter side for forming spline on a cylindrical shape part 41 of the drum shape rotary member (brake hub 4). The lubricating oil hole 5 is formed at a position shifted to a circumference direction from a center CL of groove width of a bottom part of the groove 42 (retardation side position P1) and passes through the cylindrical part 41 in a radial direction.