In the coordinate detection of resistive film system, detection of the coordinates of simultaneously designated two points is made possible. On a touch panel composed of two conductive films, whether input is made in a point or simultaneously at two points is judged by a current monitor. Simultaneous inputs at two points decrease the apparent resistance of the conductive film, and can be detected by an increase in the current. If the input of a point is identified, the coordinate data of the input point are retained as latest coordinate data in a RAM. If simultaneous inputs at two points are identified, coordinate data are obtained from the coordinate data retained in the RAM and from the potentials in the x and y directions, obtained from two conductive films constituting a touch panel, through amplifiers, and are outputted, together with the coordinate data retained in the RAM, as the coordinate data of the two points.