To solve such problems that oil seal using heat insulating raw material is expensive, the oil seal is easily broken at the time of set-up since it is soft, reliability is reduced, in a conventional hydraulic continuously variable transmission wherein the life is prevented from shortening with hardening caused by deterioration by using the heat insulating raw material for the oil seal in a pump shaft or a motor shaft, since operating oil in a casing exceeds a high temperature at operation.

The operating oil in an oil tank T which is absorbed by a charge pump 101 and which is forcibly supplied into a charge circuit 32c of a hydraulic continuously variable transmission 10, is passed near either one of the oil seal 56 used for a driving shaft 21a part as the pump shaft, and the oil seal 57 used for an output shaft, 22a part as the motor shaft, or both of them.