To provide a laser visibility meter by which a measurement can be performed in real time without a strict calibrating operation.

In a laser visibility meter, a polarized laser oscillator 12 which oscillates polarized laser light 11 is provided, a polarization rotating element 14 (e.g. a half-wave plate which is turned around the axial center) which is situated at the front of the polarized laser oscillator 12 and which turns the polarization face of the polarized laser light by 90° is provided, a beam splitter 16 which is situated at the front of the polarization rotating plate, and by which the polarized laser light is transmitted or reflected to a direction at right angles to the polarization face of the polarized laser light according to the polarization face is provided, quarter-wave plates 18a, 18b which are situated respectively on the transmission side and the reflection side of the beam splitter 16 are provided, a reflecting mirror 20 by which the laser light transmitted through the quarter-wave plate 18b on the reflection side is reflected to the same direction is provided, and a photodetector 22 which is situated on the opposite side of the reflecting mirror 20 by sandwiching the beam splitter 16 is provided. An MOR (a visibility) is computed on the basis of a change in the laser light detected by the photodetector 22.