To provide a device for inspecting optical member and a method for inspecting an optical member wherein good/bad judgement about the plane assigned the close to the image of an object in a finder is performed more strictly compared to other position.

At completion of a finder, a real image of an object is formed on the first plane P1 of a poloprism P by an objective lens. At inspection, the first plane P1 of the poloprism P is so provided as to face an imaging lens L, while the light, for lighting, is introduced from the fifth plane P5. In this case, the angle range of the lighting light at each position in the Porro prism P is limited to the range of solid angle when the fifth plane P5 is viewed from the position. Therefor, with a defect on the first plane P1, entering of scattering light caused by defect in the imaging lens L is least possible, and the defect is projected as a dark a part of high contrast. As a defect position goes away from the first plane P1, the scattering light caused by defect is more likely to enter the imaging lens L, for lower contrast of image.