PURPOSE: To improve safety of working where the danger that an operator's hand is caught between a detecting stage and a substrate mounting stage is eliminated by fixedly stopping the detecting stage which is descended by a handle at the drop position.
CONSTITUTION: When a handle 8 is turned, a clank 11 is turned to pull a connecting rod 12, so that a detecting stage 3 is lowered against a spring 4 as indicated by a two-dot chain line. The detecting stage 3 hits a stopper 13, and becomes unable to fall further. When the detecting stage 3 is lowered to this position, an engaging projecting piece 15 is engaged with an engaging piece 16, and therefore the detecting stage 3 is held at the dropping state. Thereafter, when a solenoid 9 is magnetized, a coupling point 18a is pulled and the engaging piece 16 is pulled by a coupling rod 18, thereby disengaging the projecting piece 15. As a result, the detecting stage 3 is raised to a position shown by a solid line owing to the urging force of the spring 4. Subsequently, a substrate mounting bed 20 is raised and a detecting pin 7 is in touch with a substrate 5. Then, checking of the substrate 5 is conducted. Accordingly, a dangerous possibility that an operator's hand be caught between the detecting stage and the substrate mounting bed is removed, thereby improving the working safety.