PURPOSE: To aim at enhancing the durability of a hydraulic motor by providing a relief valve which opens when the hydraulic pressure of a replenishing oil passage exceeds a set pressure, and by connecting an oil passage to the relief valve, for leading oil into a lubrication chamber in a hydraulic motor when the relief valve is opened.

CONSTITUTION: A vehicle hydraulic continuously variable transmission CVT transmits the power of engine F through an input shaft 2 so as to drive a fixed displacement hydraulic pump P and a replenishing pump F, and therefore, wheels W are driven in a stepless manner through a hydraulic closed circuit C, a hydraulic motor M, front and rear gear units G and a differential gear D. Further, discharged oil from the replenishing pump F is fed into the hydraulic closed circuit through an oil passage 137 so as to replenish for lost amount, but when the pressure of the passage 137 increases exceeding a predetermined value, a relief valve 50 is opened so that relieved oil whose pressure is regulated by a pressure control valve 150 is sufficiently fed into a lubrication chamber 75 in the hydraulic motor M so as to ensure lubrication for shoes and a swash plate. Thus, it is possible to enhance the durability of a hydraulic motor.