To provide a fine working device capable of efficiently performing fine working using a rotating tool for fine working such as an extra fine drill.

The fine working device 1 is constituted such that a spindle shaft 2 is supported by air static pressure type radial bearings 5, 6 and thrust bearings 7, 8, it is rotated at high speed by an air stream of a constant flow rate at a constant pressure fed through a nozzle 12 and a fine hole is provided on a work W by the extra fine drill 4 mounted to a distal end thereof. In the device, when excessive load is applied to the extra fine drill 4 and the spindle shaft 2 is rearwardly pressed and moved, the movement in the thrust direction is detected by a capacitance type thrust sensor 15 installed on the shaft part 2b at a rear end side. A control part 20 stops feeding or rotation of the spindle shaft 2 when it determines that the excessive load state is generated based on the sensor output. Thereby, breaking or the like of the extra fine drill 4 is previously prevented.