An inspection apparatus includes beam generation means, a primary optical system, a secondary optical system and an image processing system. Irradiation energy of the beam is set in an energy region where mirror electrons are emitted from the inspection object as the secondary charged particles due to the beam irradiation. The secondary optical system includes a camera for detecting the secondary charged particles, a numerical aperture whose position is adjustable along an optical axis direction and a lens that forms an image of the secondary charged particles that have passed through the numerical aperture on an image surface of the camera. In the image processing system, the image is formed under an aperture imaging condition where the position of the numerical aperture is located on an object surface to acquire an image.