This report discusses about effects of the tool edge serration on the brittle cracking in the ball endmill process on the soda lime glass. To observe the effects of the serration, cutting experiment was performed by the single crystal diamond (SCD) ball endmill of which cutting edge is machined triangle serrations by focused ion beam (FIB) machine tool. These serrations were machined with change in their amplitudes and a constant period to observe effects of the amplitude and apical angle of the serration on the cracking. In this experiment, the brittle cracking was changed by the serration's amplitude. Especially it was suppressed at the specific amplitude.