PURPOSE: To achieve a switching of a reference measuring distance with a non-contact probe with simple work while preventing possible error of a measurement data in the switching.

CONSTITUTION: A first photodetecting lens 161 and a first photodetector 181 and a second photodetecting lens 162 and a second photodetector 182 are arranged in the perimeter of a light emitting section 12 to share an optical axis from the light emitting section 12. A measuring reference distance L01 with the first photodetecting lens 161 and the first photodetector 181 is differentiated from the measuring reference distance L02 with the second photodetecting lens 162 and the second photodetector 182.