This paper discusses a low cost head-supported eye tracker. To measure the coordinates associated with a subjects gaze point fallen on a monitor, the subject places his head on a head support and keeps his head fixed. Meanwhile, a camera is used to capture images of the subjects left or right eye. The subjects gaze point fallen on a monitor can be determined according to the relative position of the pupil and glint in an eye image. This paper presents not only the principle of this eye tracker, but also the methods used to detect the pupil and glint in an eye image. At last, this paper presents some experimental results, and the experimental results show that the maximal average error of the experimental apparatus is 15 pixels or 0.4 in degrees.