The present invention provides a stitch measurement method for making a plurality of partial measurements, and obtaining an overall shape by combining partial measurement results, including a step of dividing, on lattices, each peripheral partial measurement region including an external portion of an overall measurement region into a first region inside the overall measurement region and a second region outside the overall measurement region, and dividing each central partial measurement region which does not include any external portion of the overall measurement region into a first region and a second region according to division patterns of the peripheral partial measurement region, a step of formulating first orthogonal function sequences on the first regions, and a step of defining linear combinations of respective functions of the first orthogonal function sequences on the first regions as first system errors for the respective partial measurement regions on the overall measurement region.