The technology has been recently known of inputting positions on tablets with input devices such as stylus pens. Here, various kinds of technology are known as the technology of detecting the inclination of the input devices. Examples thereof include the technology of detecting the inclination of the input devices with sensors incorporated into the input devices. Further, the technology has been known of detecting the inclination of the input devices from the distribution of the induced voltages generated in tablets when the input devices come into contact with or approach the tablets (see, for example, Patent Literature 1).