To obtain a high-speed resolution and good detection sensitivity and to make it possible to guarantee the quality over a long period, by magnifying an inspection object illuminated by a luminaire unit one-dimensionally diffusing beam light with a microscope as a two-dimensional image, and detecting a one-dimensional image corresponding to the diffusion radiation plane of the two-dimensional image.

A luminaire unit 2 is provided with a laser unit 2a, a polarizer 2b, and a projector 2c, and it is optically connected to a microscope 3 via a laser tube lens 8. The microscope 3 is provided between in inspection object S on a stage 4 and a sensor 6, and the inspection object S illuminated by the luminaire unit 2 is magnified as a two-dimensional image. The return light (c) reflected from the inspection object S on the stage 4 transmits a polarization beam splitter 3a toward the sensor 6, the return light (c) is prevented from reaching the luminaire unit 2, thereby the sensor 6 can detect a one-dimensional image corresponding to a beam radiation plane without receiving noise from the return light (c).