PURPOSE: To manufacture high reliability products free of process work error by installing a memory device which monitors a signal from a sensor, lights on or off an indicator under control, and informs of an unmounted manual insertion component resultant from the lack of attention.

CONSTITUTION: Each component supply jig 1A, 1B, and 1C, etc., are provided with a sensor 2 which detects taking out of each component, and an LED indicator 3, which indicates a take out state of each component. When the LED indicator 3 is in component take out demand mode, the indicator is lit up. When component taking out is detected by the sensor 2, and confirmed, the indicator is turned off. A control device 4 (designed to prevent the lack of attention), inputs a detection signal transmitted from each sensor installed to each component supply jig 1A, 1B, 1C, etc., and determines whether each component is properly mounted or not. It is an announcing device which informs of the result of determination as well as a control device which lights on or off each LED indicator 3 under control. This system is designed to be capable of connecting up to 20 sets of various component supply jigs.