A wafer inspection apparatus includes: an objective lens on an optical path of first and second input beams; and an image sensor configured to generate an image of the wafer based on scattered light according to a nonlinear optical phenomenon based on the first and second input beams, wherein the first input beam passing through the objective lens is obliquely incident on the wafer at a first incident angle with respect to a vertical line that is normal to an upper surface of the wafer, the second input beam passing through the objective lens is incident on the wafer at a second incident angle oblique to the vertical line that is normal to the upper surface of the wafer, and the first and second incident angles are different from each other.