PURPOSE: To reduce the consumption of cutting oil considerably and prevent the fouling of a machine, the floor surface, and the like caused by the drip and splash of oil while improving productivity through the sharp reduction of oil sticking quantity to a workpiece so as to dispense with the cleaning of the workpiece.

CONSTITUTION: Cutting oil 2 fed from a hydraulic power source 3 is regulated by a throttle valve 5A or an oil quantity regulating valve 5B so as to lead a trace quantity of cutting oil as oil drops 2A to an oil feed wire 6. An oil film or an oil sump 2B is formed at a ring part 7 provided at the tip part of the oil feed wire 6, and a cutting tool is passed through this oil film or oil sump 2B to feed the cutting oil to the cutting tool 1.