PURPOSE: To shorten a video processing time by irradiating a printed board by plural light sources arranged hemispherically, cylindrically, or conically, taking the optical axis of a TV camera as a center axis and fetching an image of a solder surface.

CONSTITUTION: The TV camera 6 which has a lens 7 and a filter 8 is arranged vertically over the solder surface 2 of the printed board 1. A hemispherical light sources 9 is fixed to the TV camera 6 while consisting of hemispherical members 10 and 10' as outer frames and plural spot light sources 11 which are arranged on their internal surfaces and represented by electric lamps or light emitting diodes. When both an unsoldered land and the solder surface 2 are present in the same visual field of the TV camera 6, high-brightness reflection is caused by only the solder surface 2, thereby easily discriminating between the land and solder surface 2.