Provided is an operating method of a measuring apparatus measuring a wavefront of a target. The operating method includes measuring a measurement wavefront on the basis of the wavefront of the target, measuring reference slope information and first to third slope information respectively corresponding to a reference direction and first to third directions on the basis of the measurement wavefront, obtaining first to third rotation angles on the basis of the measured reference slope information and first to third slope information, and outputting a wavefront of which an error is corrected, which is generated by rotation errors on the basis of the obtained first to third rotation angles, wherein the first to third rotation angles are differences in angle between the reference direction and the first to third directions.