In order to inspect a board, firstly, a measurement area is set on a board, and reference data and measurement data of the measurement area are acquired. Then, a plurality of feature blocks is established by a block unit so as to include a predetermined shape in the measurement area, and a merged block is established by merging feature blocks overlapped in the feature blocks. Thereafter, a distortion degree is acquired by comparing reference data and measurement data corresponding to a feature block except for the merged block and/or the merged block, and the distortion degree is compensated for, to set an inspection area in the target measurement area. Thus, an inspection area, in which distortion is compensated for, may be correctly set.