PURPOSE: To enable to perform automatic coating to a work, by providing a sensor for detecting a work, a shutter existent at the emitting or accepting opening of said sensor, a rod for moving a work, a nozzle for coating a work and a means for inhibiting the invasion of mist into said emitting or accepting opening.

CONSTITUTION: A sensor 9 is provided at a base 7 to detect the presence of a work, and a shutter 16 is provided at the emitting or accepting opening 10 of said sensor 9. A rod 14 is attached to the base 7 to move said work while engaging the rod with the work, and a nozzle 21 is provided at the base 7 to coat the work. In addition, air is supplied to a space between the shutter 16 and the emitting or accepting opening 10 by an air-purging means comprising an air- supply nozzle 20, a hollow part 8a, a small slit 19 and a slit 10b, to inhibit the invasion of mist into the emitting or accepting opening part 10. Hence, coating can be performed while automatically detecting and moving the work, and the detecting action of the sensor can be certainly performed while inhibiting the invasion of mist into the sensor.