PURPOSE: To enable the determination of poor detection state and the type thereof quickly at a look, by display an image of a substrate to be inspected with a video camera in superimposition with a marker indicating defective parts.

CONSTITUTION: A substrate 1 to be inspected is taken with a video camera 12 and a video signal is fed to a display unit 10 through a frame memory 13 and a synthesization circuit 14 to display an image of the substrate 1. The X-Y coordinate at a poorly detected part is inputted sequentially through an interface 16 and a CPU7 by way of a probe pin 15 viewing the circuit pattern of the substrate 1 displayed to be memorized into a RAM11 and a ROM17. On the other hand, the CPU7 checks the circuit pattern for quality through probe pins 4aW4d each one end of which is in contact with the circuit pattern on the substrate 1 and when any deficiency is detected, the corresponding pin number and the state of the deficiency are memorized into the RAM11. A color marker corresponding to the quality acceptance or rejection, and the coordinate value of the defective part are sent out to a VDP9 and a color display for the defective part is given on the image of a display unit 10 through the synthesization circuit 14.