Abstract: A method of grinding the notch of a thin workpiece, for example, a semiconductor wafer in the circumferential direction and the thickness direction by arranging a rotating disk-form grinding wheel and a semiconductor wafer to be ground with said wheel in such positions that the respective planes orthogonally cross with each other, moving said wheel in an axial direction of the spindle or rotating said semiconductor wafer upon the center thereof, moving said semiconductor wafer in a direction of approach to or alienation from said wheel, and moving said wheel in a direction to cross orthogonally with said axial line direction and direction of approach to or alienation from said wheel, and an apparatus therefor.