A defect inspection system can suppress an effect of light from a rough surface or a circuit pattern and increasing a gain of light from a defect to detect the defect with high sensitivity. When a lens with a large NA value is used, the diameter is 10a, an angle between the sample surface and a traveling direction of the light from a defect being α1. A system receives the light from the defect at a reduced elevation angle α2 with respect to the sample surface to reduce the scattered light, and to increase the light from the defect. The diameter 10a is smaller than the diameter 10b, resulting in a reduction in the ability to focus the scattered light. When a lens having a diameter 10c is used, the lens interferes with the sample. To avoid the interference, a portion of the lens interfering with the sample is removed.