To inspect the height of wire efficiently after wire bonding.

A wire 6 is shot with the focus of a camera 8 fixed at a reference height to obtain the brightness distribution of the wire 6 in a cross direction from the obtained wire image. The degree of fuzziness is numericallyexpressed by the brightness distribution, and the relation between the numerically-expressed result and dislocation amount from the reference height in a height direction is obtained previously as a height conversion table. For wire height inspection, the dislocation amount is obtained from the height conversion table based on the fuzziness degree of the wire image, therefore, the height of the wire 6 can be obtained without any adjustment of the focus to the wire 6 at every time by moving the camera 8 vertically, thus it is possible to conduct wire height inspection after wire bonding promptly.