1. A metrology instrument for measuring and inspecting deviations between a pair of elements of a pattern to be stitched within an image, said metrology instrument comprising: a means for obtaining an image pattern for inspection, said image pattern having a stitching part at which a pair of elements of said image pattern are stitched to each other along a straight boundary line extending along said stitching part; a &Dgr;X-measuring device for measuring deviation &Dgr;X between stitched elements of said image pattern along said straight boundary line; a storing means for storing two sets of data about images indicating dose distributions in memory, said dose distributions being calculated by a simulation method under the condition that an energetic beam is used when said elements of said pattern are transferred; an image superimposing means for shifting one of the images indicating the dose distributions by said &Dgr;X along said straight boundary line and by a desired amount &Dgr;Y in a direction vertical to said straight boundary line relatively to the other and superimposing both of said images indicating the dose distributions; and an image comparator for taking the correlation between image data obtained for said inspection and image data produced by the superimposing by comparing these two kinds of image data.