To provide a technique easily and precisely measuring straightness of a stage moving in a prescribed direction while suppressing the costs for measurement.

The central position of a straight linear pattern 21 in an X axis direction at each point is measured when a pattern body 2 having the straight linear pattern 21 on its upper surface is moved in Y axis direction for each of the cases when the pattern body 2 is fixed at a first position POS1 of the stage 1 and when it is fixed at a second position POS2 shifted by a prescribed length parallel to the moving direction of the stage 1 (+Y direction). By obtaining the difference between the obtained measurement results D1, D2, the displacement amount of the pattern 21 itself in the X axis direction is canceled out, and the amount of variation of the position of the stage 1 during movement at each position in the X axis direction is calculated. Further, by cumulatively adding the differential results, the displacement amount (movement errors, straightness) at each position in the X axis direction of the stage 1 moving in the (+Y) direction is calculated.