A line of sight detecting method includes estimating a face direction of an object person based on a shot face image of the object person, detecting a part of an eye outline in the face image of the object person, detecting a pupil in the face image of the object person, and estimating the direction of a line of sight of the object person based on the correlation of the pupil position in the eye outline and the face direction with respect to the direction of the line of sight, and the pupil position and the face direction of the object person.