PURPOSE: To prevent a mistake on the suction of a chip by arranging one of a light-emitting means or a light-receiving means toward a suction port for the chip in a collet and disposing the other toward the suction port for the chip at a position in the moving range of the collet.

CONSTITUTION: A light-emitting element 22 is arranged in a path for vacuum- suction of a collet 20. Beams from the light-emitting element 22 are outputted in the direction of a suction port for the collet 20. On the other hand, a light- receiving element 26 is disposed to the lower section of the suction port for the collet 20, and beams from the element 22 are received. The element 26 is arranged at a proper position in the moving range of the collet 20. When a mistake on the suction of a chip 15 is generated, beams from the element 22 are received to the element 26 because of no chip 15, thus determining the generation of the mistake on the suction of the chip 15.