A line-of-sight detection method includes detecting an eye region of a subject from an image, determining whether a position of a boundary between a pupil and an iris is detected from the image based on a brightness change in the eye region, executing, in accordance with a result of the determining, at least one of first processing in which a position of a center of the pupil is detected based on an outline of the pupil and second processing in which the position of the center of the pupil is detected based on another outline of the iris, and detecting a line of sight of the subject based on the position of the center of the pupil detected by the at least one of the first processing and the second processing.