Abstract: A sighting direction detecting device including a TV camera which is disposed to face a human being and picks up an image of light invisible to human beings, a first illuminator which is disposed in a coaxial system with the TV camera and illuminates a human's eye-ball portion with light which is invisible to human beings, a second illuminator which is disposed at a different place from the first illuminator and illuminates the human's eye-ball portion with light which is invisible to human beings, a first calculator for calculating an equation of a line passing the pupil center position of the eye-ball, an equation of a line passing the reflected-light position of the first illuminator and an equation of a line passing the reflected-light position of the second illuminator on the basis of the image which is picked up by the camera, a second calculator for calculating the center position of a cornea ball on the basis of the equation of the line passing the reflected-light position of the first illuminator and