Surface profile measurement apparatus

A surface profile measurement apparatus is provided. The surface profile measurement apparatus includes a conversion optical system dividing the picture of the irradiation position of the laser beam in a length direction of the area into a plurality of pictures by using a plurality of conversion optical paths, each comprising three or more optical paths; and an imaging part having an imaging lens and collectively photographing the pictures. The mirrors are arranged as the following: the mirrors included in the conversion optical paths extend respectively in a direction corresponding to the length direction of the picture with a numerical aperture of the imaging lens and a length corresponding to an optical path length from the irradiation position of the laser beam to the mirror, and a mirror constituting a different conversion optical path is not located on the optical path of each of the conversion optical paths.