A machine tool wherein a unit (42) for supplying machining fluid to the machining area of a tool (T) when a work (W) is machined with the tool (T) detachably fitted to the main shaft (12) of the tool is provided with a fluid ejecting port (44a) at the tip of a fluid supplying nozzle (44) which gives a movement in the radial direction and a movement in the circumferential direction, each relative to the axis of the main shaft (12), by moving means (54, 74) to the periphery of a main shaft head (10) having the main shaft (12) via a supporting rod (48) and a supporting bracket (50). The tool is provided with an automatic tool measuring unit (30) for measuring the diameter of the tool (T) fitted to the main shaft (12) in order to render the set positions of the fluid supplying nozzle (44) in the radial and circumferential directions adjustable and variable according to the type of the tool and the variation in tool diameter with the progress of machining.