To try to enhance durability for a hydraulic pump and a hydraulic motor by lowering the temperature of oil stored in the housing of the hydraulic type continuously variable transmission.

This hydraulic type continuously variable transmission is so constituted that fluid connection is made between a hydraulic pump P driven by a prime mover E and a hydraulic motor M driven by hydraulic oil fed from the hydraulic pump by means of closed circuits 1 and 2 provided with a relief valve 10, and concurrently the device comprises the hydraulic pump P and the hydraulic motor M housed in a common housing. In this case, after relief oil developed when the relief valve 10 is actuated to adjust pressure, has been cooled by an oil cooler 14, let the aforesaid oil be joined reservoir oil in the housing.