PURPOSE: To simplify the driving structure of an oil pump, and prevent the mixing of a control oil with an engine oil, by locating the oil pump outside a crank case of an internal combustion engine, independently providing supply systems for the control oil and the engine oil, and returning the control oil leaked from a mounting portion of the oil pump to the supply system of the control oil.

CONSTITUTION: When a rotational speed of a crankshaft of an internal combustion engine becomes greater than a predetermined speed, power is transmitted through gears to a continuously variable transmission, and is further transmitted through gears to a driving system. An oil pump 36 is driven through gears 50 and 45 by the operation of the internal combustion engine. Then, a control oil is pumped to a frictional transmitting portion, etc. of the continuously variable transmission. Even when the control oil in a pump chamber 47 leaks from a gap between a drive shaft 44 and a mounting portion 41 to a crank case 5, it is gathered into a passage 48, and is returned through a return pipe 49 to an oil pan. Accordingly, it is possible to prevent the mixing of the control oil with an engine oil.