To provide a numerical controller for a machine tool capable of shredding chips efficiently along one path by making oscillating motion involving synchronization between multiple axes and intermittently making cutting-out motion and cutting-in motion. A controller is for a machine tool used for thread cutting of a work as a target of the thread cutting using multiple axes, comprising: a movement command generation unit that generates a movement command for the multiple axes; an oscillation command generation unit that generates an oscillation command for causing a work rotary axis, a tool feedaxis, and a radial direction motion axis to make oscillating motion involving synchronization between these three axes, the oscillation command being for causing a cutting tool to make motion of departing from the work while making cutting-out motion on the work and make cutting-in motion on the work intermittently; and an adder that adds the movement command and the oscillation command and outputs a total movement command resulting from the addition.