Control device for machine tool

A machine tool controller for a machine tool that performs machining while causing a tool and a workpiece to oscillate relative to each other, the machine tool controller comprising:

• an oscillation command generation unit that calculates an oscillation amplitude and an oscillation frequency from a machining condition and generates an oscillation command;
• and
• a control unit that causes the tool and the workpiece to oscillate relative to each other based on a superimposition command generated by superimposition of the oscillation command generated by the oscillation command generation unit on a position command or a position deviation, wherein
• the oscillation command generation unit changes at least one of the oscillation amplitude or the oscillation frequency during the machining, after it is determined that the machining has entered a stable state based on a spindle load, a spindle speed, a spindle speed deviation, a spindle speed fluctuation, a feed shaft load, a feed shaft speed, a feed shaft speed deviation, or a feed shaft speed fluctuation.