Orbit detector

The object is to provide a track detection device on a probe to reduce its contact weight. To achieve the object, the probe 1 is formed in an angular shape, and the end surface 10 at the front end is formed in a rectangular shape having one side used as a linear contact side 11, and R formed at both ends. The linear contact side 11 contacts with the measured object in the direction perpendicular to the track, so as to increase the contact area and reduce the contact weight, and also avoid increasing the contact area in the track direction without enlarging the detection spacing and without increasing the wear.