Abstract: An input device detects a sight line position using an elliptical parameter method based on captured data of two cameras of a left eye and a right eye. In the elliptical parameter method, since the accuracy becomes low as an ellipse approximates a circle, weighting is performed in advance for a section on a display image indicated by a sight line. For example, a weight for a section D5 in the nearest distance from a normal line position is set to 0.3. Next, a weight for sections, which distances from the normal line position are next to the section D5, is set to 0.5. Last, a weight for sections in the remotest distance from the normal line position is set to 0.8. Last, a center sight line coordinate value according to both eyes is calculated based on a determined sight line coordinate value corresponding to both cameras.