A power transmission system comprises a hydrostatic continuously variable transmission constituted by integrally and coaxially coupling a pump cylinder of a swashplate type hydraulic pump with a motor cylinder of a swashplate type hydraulic motor. The transmission is rotatably supported at its opposite ends on a bearing. A first transmission device connected to an engine is connected to an input member of the pump from one side of the transmission, and a second transmission device connected to a load member is connected to an output member of the pump on the radially opposite side of the transmission. The first and second transmission devices are disposed adjacent each other near one end of the continuously variable transmission. This permits the points of action of loads on the input and output members from the first and second transmission devices to be placed in close vicinity to each other, thereby reducing the swinging moment and the flexing moment acting on the transmission due to these loads.
