A pitch measurement method of performing noncontact measurement of a pitch of target portions, the target portions being provided in an object and adjacent to each other, includes moving the object such that the target portions move along a same path, continuously acquiring and storing optical data of the target portions passing a predetermined position on the path from a fixed position, while focusing on the predetermined position, calculating a focusing evaluation value representing a degree of focus at an area corresponding to the predetermined position, using a movement distance of the target portions as a variable, according to a relationship between the optical data and the movement distance, and obtaining a point group of combinations of the movement distance and the focusing evaluation value, and applying a reference curve to the point group, thereby determining the pitch based on a position where the reference curve is applied.