To prevent creeping start when starting an engine, and to surely stop a vehicle in a slope, in regard to a hydrostatic continuously variable transmission provided with a hydraulic servo mechanism of structure for controlling tilting of a movable swash plate connected to a piston by supplying the charge pressure through a swash plate angle control valve in order to slide the piston.

At least one of pressure receiver chambers 20a and 20b is provided with a positioning means 89 for positioning the piston 21 at a neutral position, where supply of pressure oil to the pressure receiver chambers 20a and 20b is stopped, in relation to a spool 22 positioned corresponding to the neutral position of a movable swash plate of a hydraulic pump during the time when an engine for driving the hydraulic pump for supplying pressure oil to the pressure receiver chambers 20a and 20 is stopped.