MARK DETECTION METHOD

PROBLEM TO BE SOLVED: To provide a mark detection method capable of accurately detecting an edge of a mark being a detection object.SOLUTION: The mark detection method includes: a step of differentiating a two-dimensional image including linear marks extending in a Y direction, in an X direction and then performing projective addition in the Y direction; a number-of-edges detection step of detecting the number of edges present in the Y direction during the projective addition, for each region in the X direction; an addition value correction step of reducing an addition value for each region in the X direction after the projective addition in the case that the number of edges for each region in the X direction, which has been detected in the number-of-edges detection step, is equal to or smaller than a set value; and an edge detection step of detecting edges of the linear marks on the basis of the addition values for respective regions in the X direction after the projective addition, which have been corrected in the addition value correction step.