To provide an automatic lathe on which a vibration cutting unit or a step vibration cutting unit is mounted and in this case to provide the automatic lathe capable of realizing through constitution as mush as simple without needing a new drive source and a cutting method by the automatic lathe.

The automatic lathe is provided with a tool rest 1 provided with a rotary drive source 10 and a cutting tool 73 removably mounted on the tool rest 1, and a vibration cutting unit 7 to apply a cutting work on a work by applying vibration radially on the cutting tool 73 by utilizing drive from the rotary drive source 10 of the tool rest 11.