PURPOSE: To check accurately whether there are projecting materials like pins provided on a work or not in a short time, by positioning relatively an object to be checked and a pin supporting body and fixing one of them and moving the other.

CONSTITUTION: An object W to be checked is positioned under a pin supporting body 1, and the pin supporting body 1 is allowed to fall toward the object W to be checked, and then, lower ends of detecting pins 6 are brought into contact with projecting materials 21 on the way of fall to stop detecting pins 6, and only the pin supporting body 1 falls to a set position. Since conductor parts 7 of detecting pins 6 are separated from the upper surface of a conductor base 2 therefore, a circuit is held is the open state, and an indicator lamp 13 is not lit even if a changeover switch SW is operated to close each contact. If projecting materials 21 are not provided in prescribed positions of the object W to be worked, detecting pins 6 corresponding to these positions fall to the set position together with the pin supporting body 1, and therefore, conductor parts 7 of detecting pins 6 are held in the state contacting with the conductor base 2, and the circuit is in the close state, and the indicator lamp 13 is lit by the operation of the changeover switch SW. Thus, the presence or the absence of projecting materials 21 is found by lighting or extinction of the indicator lamp.