First, the development of the chatter vibration is observed using several turning tools having various cutting edge configurations and in the conditions in which there are different levels of interference between the flank of the tool and the workpiece. Next, the exciting energy provided by the contact of tool flank and workpiece is calculated using an interference model at the tool flank which includes an elastic deformation of workpiece. This theoretical result agrees qualitatively with the experimental result concerning the development of chatter vibration. The energy-supplying mechanism in primary chatter vibration of a turning tool is clarified by examining the foregoing results collectively.