To provide a polishing device, automatically replacing a polishing roller, and automatically performing calibration.

This polishing roller replacing device includes: a polishing roller storing part having a driving motor and a transmission belt for transmitting the power of the driving motor, storing the polishing roller and setting the polishing roller to be replaced in a standby position; an arm rotatably supported, provided with the polishing rollers at both ends thereof, and having a lock head for performing removal operation; a servo motor for moving up and down the machining spindle supporting the polishing roller of the polishing machine; a sensing and measuring device for sensing the position of the replaced polishing roller and supplying the data for calibration; a pressure device for supplying the power required for the operation of the arm; a pressure control valve for controlling the magnitude of pressure supplied by the pressure device; and a programmable controller for controlling the operational relationship between the polishing roller storing part, the arm, the servo motor, the sensing and measuring device, the pressure device and the pressure control valve.