A wire electrical discharge machine (10) obtains position error information (”x, Ay) indicating a position error in a planar direction (X-Y) in a workpiece (W, W1, W2) placed on a mounting table (14) after relative positions between a first guide unit (20) and a second guide unit (22) are changed, and calculates a position of the workpiece (W, W1, W2) with the corrected position error in the planar direction (X-Y) in a state where a wire electrode (12) is inclined according to an inclined state of the workpiece (W, W1, W2) by using this position error information (”x, ”y).
