To make any crack be hard to occur at the peripheral side of a hole without increasing an amount of oil flowing into a one-way clutch, in this plastic stator which forms a ring plate part integrally in the axial one end of an inner circumferential cylindrical part or the vicinity toward the inner circumferential direction, holding an outer race of the one-way clutch integrally at the inner circumferential side of the inner circumferential cylindrical part by means of insert formation, and installed with the required number of holes piercing through the plate part in the axial direction.

A hole 9 is formed into a long hole form being longer in a direction to be crossed with the radial direction of a stator, while an opening 13 at the side of a thrust surface 5 of this hole 9 is made to be larger than an opening 14 at the side of a one-way clutch.