To prevent cavitation or transmission efficiency degradation caused by failure in the recovery of hydraulic pressure in a closed circuit due to an excessive discharge of oil through a relief valve during working, in a hydraulic continuously variable transmission to be applied to a working vehicle or the like.

The hydraulic continuously variable transmission has an input shaft 2, a cylinder block 3 securely installed on the input shaft, a pump swash plate 4 disposed in one side of the cylinder block, a motor swash plate disposed in the other side of the cylinder block, and an output member 5 integrally rotatable with the motor swash plate. The cylinder block includes a pump plunger 31, a motor plunger 32, and an oil passage that connects the pump plunger to the motor plunger. A charge check relief valve assembly 10, including a relief valve 11 for discharging oil from the oil passage and a first charge check valve 12 for supplying oil to the oil passage, is connected to the oil passage. In the hydraulic continuously variable transmission, a second charge check valve 13 is externally attached to the charge check relief valve assembly.