To provide a gear grinding apparatus enabling a worker to observe the outer peripheral surface of a screw-like grinding wheel to be shaped from the front of the apparatus and having a small number of NC control axes.

This gear grinding apparatus 1 is formed by a machining mechanism (a), a work clamp mechanism (b) formed by a spindle stock 130 and a core clamper stock 131, and a grinding wheel shaping tool mechanism (c) having a dresser 140. The machining mechanism (a) is provided with a lateral (Z) feed mechanism 11 for the screw-like grinding wheel 120, a work slitting longitudinal (X) feed mechanism 115, a grinding wheel revolving mechanism 117, a grinding wheel vertical (Y) feed mechanism 119, the screw-like grinding wheel 120 journaled to a spindle driven by a built-in motor, and a pulse generator 121. A revolving table 116 is revolved so that the diametral direction of the screw-like grinding wheel 120 is a vertical plane, and a guide table 111 is moved to the right by the grinding wheel lateral feed mechanism 112, whereby the screw-like grinding wheel 120 is moved to the front of the dresser 140, and then the rotating screw-like grinding wheel is moved forward to abut on the dresser, thereby shaping the screw-like grinding wheel.