Provided is a control device for a machine tool, the control device being capable of reliably reducing noise when gears mesh with each other and providing intended machining quality. A control device 10 for a machine tool machines a workpiece W including at least one tooth surface and comprises: a machining condition input unit 15 which can input a machining condition including at least one of specifications of the workpiece W, specifications of a tool T, a feed speed, the rotational speed of a spindle, and the number of teeth; a surface pattern calculation unit 16, which calculates, on the basis of the machining condition, a surface pattern defined on the basis of intervals of scratches occurring on a machined surface; a swing command generation unit 17, which generates, on the basis of the surface pattern, a swing command for achieving a surface pattern including a portion in which the intervals of the scratches are unequal; and a position and speed control unit 14 which carries out the machining while swinging the workpiece W and the tool T relatively to each other on the basis of the swing command generated by the swing command generation unit 17.