To discriminate existence of a notch, by forming a template for expressing characteristically a part where brightness is changed on a notch edge part, and by executing density pattern matching between the template and an inspection image.

A semiconductor package is photographed by a television camera, and the circumference of a notch is dragged by using a mouse, and brightness information of each one pixel is recorded as a template. In a figure (B), a thickly shaded part is a notch part, and a dark part, a thinly shaded part is the package surface of a gray part. As for a part where a character is written inside the notch, an operation of the degree of coincidence by density pattern matching is not executed and an operation of pattern matching is skipped, therefore a template shown by a figure (C) is obtained, and the inside of a quadrangle shows the range of the template and a central white part shows a part where the operation is not executed. As a countermeasure against incapability of recognition of the notch part because of having the same brightness as the semiconductor package surface, the thickly shade part in the figure (C) is narrowed as much as possible by using the fact that the shaded part of a step is blackened for a while.