<p>A laser output measurement mechanism includes a light splitter 2 that is disposed in a state rotated by a predetermined angle about an optical axis 6 of laser light incident thereon, and that reflects a part of the laser light according to a Fresnel reflectivity that depends on a polarization direction and an incident angle of the laser light at a reflection surface thereof, and a light detector 4 that measures an intensity of the laser light reflected by the light splitter 2.</p>
