To provide a die changing device capable of discriminating a punch die station of an upper turret for attaching/detaching a die, a die station of a lower turret, and a die to be detached or a die to be attached.

By moving a changing arm 67 for changing a punch die P and a die D to a predetermined position of the upper turret 11 and the lower turret 15, a discriminating medium 107 which is provided on the upper turret 11 to indicate the punch die fitting position, a discriminating medium 108 which is provided on the lower turret 15 to indicate the die fitting position, or a punch die discriminating medium 113 and a die discriminating medium 111 are read, and any mistakes in the upper turret position and the lower turret position for detaching the punch die P and the die D, or the upper turret position and the lower turret position for fitting the punch die P and the die D can be prevented thereby.