A line-of-sight detection device (199) includes an image data acquisition unit (202) that acquires image data of a face of a subject irradiated with detection light emitted from at least one light source (103), a line-of-sight detection unit (216) that detects a line of sight of the subject based on the image data, an image processing unit (206) that performs image processing on the image data to generate a feature image of the face and an eyeglasses reflection image indicating a reflection image of the at least one light source on eyeglasses worn on the face, and a display controller (208) that causes a display device to display the feature image and the eyeglasses reflection image in a different display form in a composite image in which the feature image and the eyeglasses reflection image are combined.
