PURPOSE: To enable resist pattern defects which are transparent to any white light source to be inspected by infrared absorption by using infrared radiation as a light source for inspection, and receiving light transmitted through a subjected for inspection at an infrared image sensor.

CONSTITUTION: A half mirror 8 and a mirror 13 are both provided in such a manner as being capable of going into and out of an optical path. The mirrors 8, 13 are retreated from an infrared optical axis and a shutter 12a is opened and a shutter 12b closed. Then light from an infrared light source 9 is transmitted through a wafer 10 from its reverse side and taken as a first image into an infrared image sensor 11. Next a stage 5 is moved and another resist pattern on the wafer 10 is similarly taken as a second image into the sensor 11. The first and second images are subjected to comparison processing and inspection by an image processor 6 and a computer 7. To observe pattern defects, the mirrors 8, 13 are placed on the optical axis and the shutter 12a is closed and the shutter 12b opened and thereby the infrared light source 9 is cut off and visual observation using a white light source 1 is made possible.