To provide a hydraulic power transmission capable of preventing the movement of a vehicle in stopping a motor.

In this hydraulic power transmission, having a closed circuit formed by communicating ports of a variable displacement pump 10 and a motor 20 to each other by means of passages 30 and 31, a charging passage 37 for supplying a fluid from a charging pump 35 to the passage 30 and 31 of the closed circuit at a prescribed pressure, and a neutralizing circuit 51 for flowing out the discharged fluid from the passage 30 of the closed circuit to the charging passage 37, when the discharging amount of the variable displacement pump 10 is very small, the neutralizing circuit 51 is provided with a neutralizing valve 50, which is closed when the pressure in the charging passage 37 is lowered to be less than a prescribed value.