To surely stop a vehicle in a slope by surely braking an engine, 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.

The pressure receiver chamber 20a in the sliding direction of the piston 21, of which neutral position is positioned at the swash plate position, is provided with an energizing means 95 for energizing the piston 21 to the maximum swash plate position, where supply of the pressure oil to the pressure receiver chambers 20a and 20b is stopped, in relation to a spool 22 positioned corresponding to the maximum swash plate position of the movable swash plate of a hydraulic motor during the time when an engine for driving a hydraulic pump for supplying the pressure oil to the pressure receiver chambers 20a and 20b is stopped.