This machine tool includes a spindle, a workpiece support section that supports the workpiece, a servo motor that rotates or moves workpiece support section relative to the spindle, and a control device that controls the servo motor, where the control device displays an adjustment screen for adjustment of at least either of a gain and a filter of the servo motor on a display device when the control device recognizes that the servo motor is newly mounted, when a machining program of the workpiece is changed, or when an operation value of the servo motor or a value calculated based on the operation value deviates from a predetermined criterion.

A numerical controller for controlling a machine receives an instruction to reestablish a machine coordinate value of a movable part of the machine and stops a servo motor driving the movable part. When the servo motor is stopped, the numerical controller acquires position information of a position detector provided to the servo motor. Then, the numerical controller updates the machine coordinate value of the movable part based on the position information, and further updates the absolute coordinate value of the movable part based on the updated machine coordinate value.