In an indoor positioning system, for establishment of a cost sharing system, the positioning information transmission device does not directly transmit positional information but performs concealment and variablization on the device ID and transmits the concealed and variablized device ID. The positioning information management server stores and manages correspondence between the device IDs and positional information, and performs conversion from the device ID to the positional information in accordance with the correspondence. Further, the problem of conflict between concealed IDs upon concealment of positioning identification information by the positioning information transmission devices, which occurs when all the positioning information transmission devices use the same secret key, can be prevented. The system can be operated even when the bit length of the device ID is short.