There are provided a measuring head moved along a guide rail, first position detection means for detecting the positions of the measuring head on the guide rail using a predetermined position on the guide rail as a reference position, second position detection means for detecting the position in a world coordinate system of the measuring head on the guide rail, and means for storing in a storage device each of the positions of the measuring head on the guide rail using the predetermined position on the guide rail as the reference position and a corresponding position in the world coordinate system with the positions correlated with each other.