1. An inspection method comprising: setting a measurement area on a board; acquiring reference data and measurement data of the measurement area; establishing a plurality of feature blocks by a block unit so as to include a predetermined shape in the measurement area; establishing a merged block by merging feature blocks overlapped in the feature blocks; acquiring a distortion degree by comparing reference data and measurement data corresponding to a feature block except for the merged block and/or the merged block; and compensating for the distortion degree to set an inspection area in the target measurement area.