To provide a machining method allowing elimination of problems due to liquid splash by injecting liquid in mist form, and capable of uniformly mixing the liquid with air in a structure using a spindle of a machine tool.

The compressed air and the liquid are separately supplied into a through hole 25 longitudinally formed in a draw bar 5 in the spindle 2 of the machining device, passed through the through hole 25 in different states, and mixed and atmized at the tip-side part of the through hole 25. This mist-like substance is made to flow out of the tip opening of the through hole 25, fed to the tip side of a machining tool along the outer periphery of the machining tool or through inside of it, and spouted from the tip side of the machining tool to a machining part to machine a work.