To accurately obtain positional information of a mobile phone, using optical wireless communication by means of illumination light.

In Figure, an emergency light or a guiding light (a lighting device) 10, which is turned on 24 hours a day, emits a visible light (illumination light) modulated, based on the information of its location. The mobile phone 20 with a visible light receiving unit (for example, camera or the like) can obtain positional information, by receiving and demodulating the visible light. When an emergency call is placed (for example, a call to police dial 110 or to fire station dial 119), the positional information obtained is automatically added to voice information as data communication.