PURPOSE: To reduce oil passage resistance in the case of using an annular clearance, formed between a torque converter sleeve and a shaft, as an oil passage, and improve assembling workability.

CONSTITUTION: Operating oil is fed to a torque converter 6 through an annular oil passage A formed by fitting a torque converter shaft 5, connected to a pump impeller 7 so as, to rotatory-drive an inner gear 3, with play to the peripheral part of a stator shaft 8. Assembly is carried out with protruding parts E, provided protrusively at four circumferential places in a part in the axial direction of the inner peripheral part of the shaft 5, as a guide.