PURPOSE: To obtain the color image of a board without using any expensive color TV camera by using a lighting part which scans two-color mixed light and a photoelectric transducer provided with optical filters for different-color light.

CONSTITUTION: A G-color detector 7 is equipped with a phototransistor Tr 42 and a G-color filter 44 and a B-color detector 8 is equipped with a phototransistor Tr 43 and a B-color filter 45. A control part 36 turns on the lighting part 10 to convert light reflected by a printed board 25-2 to be inspected into an electric signal by the Trs 42 and 43 while making an X-Y scan on the printed board 25-2 to be inspected with the two-color coaxially mixed light consisting of G-color light and B-color light. A control part 36, on the other hand, inputs the obtained G primary color signal and B primary color signal of the board 25-2 to an image input part 32 to generate GB primary color image data. Then, the control part 36 transfers this data to an image processing part 33 to generate a subtraction video signal G-B. Further, the control part 36 checks whether or not all parts 28-1W28-n are present by a decision part 35.