A refined coordinate detection method for a touch panel, which more finely measures coordinates of an object without increasing the number of infrared emitting/receiving elements, and an error correction method, which minimizes position detection errors caused by received optical level errors due to external environment or their inherent characteristics, are provided. In the detection method, received levels of infrared emitting/receiving elements corresponding to left and right ends of object are measured and stored and the levels and a maximum received level are compared to calculate the refined coordinates. In the correction method, a lower limit level at a position where infrared reception is most significantly impeded by object is calculated through a comparison calculation of maximum and minimum received levels and it is detected that an object is present at a position only when a lower limit level at that position is not greater than the calculated one.