To detect simply and surely a failure of a circuit pattern such as a defect or a minute flaw, concerning a printed circuit board having a trend of miniaturization and densification.

This device has a spectral camera 3 for detecting a spectrum on this printed circuit board 1, a spectral image taking part 4 for taking a spectral image detected by the camera 3, an analysis part 7 for analyzing the image taken by the taking part 4, a central processing part 11 for executing processing, or the like. Irradiation of illumination to the printed circuit board is executed from the tilted direction toward the board face of the printed circuit board. At the irradiation time of illumination from the tilted direction toward the board face of the printed circuit board, irradiation is executed from at least two mutually different directions.

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