A blade changer unit includes a blade chuck for holding a cutting blade, a moving unit for moving the blade chuck, and a control unit for controlling moving unit. The blade chuck has a plurality of electrically conductive grippers for holding the cutting blade. The controller detects conduction between the grippers and a boss. The control unit includes a calculator for calculating the position of a central axis of the mount from coordinates where the conduction between the holder and the boss is detected when the moving unit is controlled to bring the grippers into contact with the mount at at least three points, and a mounting/dismounting controller for mounting and dismounting the cutting blade while the central axis of the blade chuck is aligned with the central axis of the mount calculated by the calculator.