PURPOSE: To accurately inspect a printed board on which plural kinds of patterns exist by automatically allocating different inspection methods to different areas of each pattern.

CONSTITUTION: A refining circuit 4 refines binary-image data about a pattern to be inspected, and sets the line width of a signal-pattern portion to '1'. Portions where the line width is '1', other than branching points and end points, are removed from the refined image data by a one-picture-element contracting circuit 5. An inspection-area division data creating portion 6 enlarges the '1' portions of contracted image data obtained from a one-picture-element contracting circuit 5 and allocates inspection areas. An area-comparison inspection is applied to the portion of the inspection area created by the inspection area division data creating portion 6 and a design-rule inspection is applied to the signal patterns of other portions.