High precision mold grinding technique to obtain mirror surface is required which realizes minimization or omission of final polishing by skilled workers. In the previous reports, ultrasonically diamond grinding experiments were carried out to confirm ultrasonically oscillation effect for die steel face grinding. Mirror surface was obtained successfully and little abrasive worn out was found. In the above technique, the cutting edge shape of a tool affects the ground surface resulting from transcription of cutting edge. In other words, cutting edge truncation of grinding tool is required to be smooth and glossy surface. This paper describes the cutting edge truncation of diamond electroplated tools which are used in ultrasonically assisted grinding. Experiments were carried out to confirm truncation effects on the ground surface and grinding force. It was confirmed that cutting edge truncation is effective method to obtain mirror surface and excessive truncation causes large grinding force and chattering.