This paper proposes an algorithm to estimate gaze direction without on-site calibration even when the position of the head relative to the camera moves. We define eye direction as geometrical direction of the eyeball and gaze direction as long fixed looking detection in this paper. In the algorithm to detect the eye direction, a cornea curvature center is detected based on a relation model between a light source and the cornea curvature center. A shape of the pupil is approximated using the detected center by ellipse Hough transform. The eye direction is estimated as a rotation angle of the approximated pupil using a cornea curvature radius and distance between the cornea curvature center and a pupil rim. This personal information on the eyeball is essential to the eye direction detection ...