PURPOSE: To reduce the extent of power loss in a machine by installing two oil pumps being driven by an engine, and controlling them in supplying lubricating oil to be discharged out of each pump to a lubricating part via a passage selector valve being selected according to the rotational frequency of the machine such as an engine or the like.

CONSTITUTION: An inlet port of a first oil pump 4 being driven by an engine is connected to an oil pan 1 by a passage 3, and a discharge port of this pump 4 is connected to a lubricating part 2 by a passage 5. In addition, the passage 3 is connected to the inlet port of a second pump 8 being driven by the engine by a passage 7, and the discharge port is connected to a first port 11 of a passage selector valve 10 by a passage 9. This passage selector valve 10 is constituted so as to install a sliding valve body 21, being energized to the upper part by a compression spring 25, in the inner side of a casing 20 and to open or close an inner passage 20 of this valve body 21 through a sphere 23. At time of low engine speed, by way of example, this sphere 23 is pushed up by a pressure differential between these first and second ports 11, 12, and then lubricating oil out of the pumps 4, 8 is made so as to be fed into the lubricating part 2.