Abstract: A grinding wheel form defining device defines a cross-sectional form of a grinding wheel for grinding works, the cross-sectional form including a grindstone axis. Data storage is provided for storing cross-sectional forms of workpieces which are final forms in a grinding process. A grinding wheel basic form selected out of plural prestored grinding wheel basic forms, which are simple two-dimensional patterns for typical grinding wheel forms, is superimposed on a workpiece form which is read out from the data storage. A form obtained by removing the resultant superimposed form from the grinding wheel basic form is defined as a grinding wheel form. Since the grinding wheel form is defined by utilizing the superimposed form obtained by superimposing the already defined workpiece form and the grinding wheel basic form, even a complicated grinding wheel form can be easily and accurately defined.