PURPOSE: To make it possible to confirm the fitting of a work regardless of the height accuracy of a pallet by detecting the fitting state of the work by the value calculated at a control part at the time of fitting the hole of the work at the fitting plane of the pallet with a pin.

CONSTITUTION: A work 40 is attracted to a vacuum attracting tool 8, and a finger 3 is lowered until the work 40 is brought into contact with the pin 50a of a pallet 50. When the finger 3 is further pushed down by compressing a coil spring 12 by the specified quantity, the detecting part of a displacement sensor 4 is pushed up. This position is made A and memorized into a control part. A rotary actuator 9 is then actuated to rotate the work together with the attracting tool 8. At this time, the hole 40a of the work 40 goes into the pin 50a of the pallet 50, so that the rotation of the work 40 is halted, the work 40 is pushed down by the resilience of a spring 12, and the sensor 4 is also lowered into the B position. The value of this B is fed to the control part, B-A is calculated, and if this calculated value is 0, it is confirmed that the work 40 is not fitted correctly at the pin 5a.