A numerical controller has a tool retraction function for retracting a tool so as not to damage the machined surface of a workpiece when machining of the workpiece by a machine tool is interrupted. The numerical controller identifies a machining method for the machining to be interrupted when a command to interrupt the machining is detected, determines the direction of the retraction of the tool, based on the identified machining method and the feed direction and the rotation direction of a spindle in the machining to be interrupted, and generates a movement path of the tool in the determined retraction direction.