To reduce lubricating oil to the necessary minimum oil feeding quantity while maintaining oil feeding pressure to make lubricating oil reach a bearing and a gear of a shaft to rotate at high speed.

Self-excited vibration is generated by properly setting pressure of a supply system 10 reaching an oil jet from an oil pump 1 to a time constant and characteristic frequency of a pressure governing valve 12, and oil is fed while maintaining the maximum oil feeding pressure by timely changing oil feeding pressure in the case of feeding lubricating oil to be supplied from the capacity type oil pump 1 by the oil jet. Consequently, total oil feeding quantity is reduced by timely changing oil feeding pressure by using pulsation of oil feeding pressure.