The poor machinability material such as austenite stainless steel(STS304) is emphasized on the wide use of HSSE for the tapping operation. The difficulty can be entirely to tapping torque due to chip formation through the hole of tap. The object of this study is to investigate tap geometry affecting the tapping torque from a practical point of view. The study shows that the optima tapping torque is affected by the tap geometry and cutting condition for STS304.