A positioning system includes an illumination device, a terminal, and a positioning server. The illumination device transmits identification information. The terminal transmits the identification information received from the illumination device, to the positioning server. The positioning server uses the identification information received from the terminal, thereby searching an illumination installation position database registered in advance so as to identify the terminal position. This eliminates power supply for positioning infrastructure and facilitates attachment to a ceiling, thereby realizing the positioning infrastructure at a low cost.