To provide a hydrostatic continuously variable transmission stabilized in control of a movable swash plate by a hydraulic servo mechanism and capable of excellently controlling a load with a load control mechanism, in regard to structure provided with a variable capacity type hydraulic pump and a hydraulic motor and for controlling a load by using pressure oil of a main oil passage connecting the hydraulic pump to the hydraulic motor.

A constant flow rate valve 55 for limiting flow rate of the oil to be led into a swash plate angle control valve 23, which is formed in each of hydraulic servo mechanisms 2 and 102, is provided in oil passages 19 and 19 for leading charge pressure oil from a charge oil passage 16 to each of the hydraulic pump 10 side hydraulic servo mechanism 2 and the hydraulic motor 11 side hydraulic servo mechanism 102 at a position, where flow rate of the charge pressure oil supplied to the load control mechanisms 4 and 104 is not limited.