An apparatus for measuring groove positions of a workpiece includes a sensor for detecting grooves formed on the workpiece and a position sensor for detecting angular position of the workpiece with respect to a predetermined standard position, a measuring cycle memory means for storing several predetermined measuring cycles, a data input means for imputting and storing groove data indicating groove shape, a measuring control means for selecting a specific measurement cycle from the measurement cycle memory means based on the groove data to execute selected measurement cycle, a calculation processing means for executing calculation processing for determining the center positions of grooves, and a data output means for outputting and displaying the results of the calculations in order to inform an operator of the center positions of the grooves.