Abstract: It is an object of the present invention to provide a system with which 3-dimensional position can be accurately measured. Plural UWB transmitter-receivers (1), periodically transmitting PN codes of M system and preliminarily disposed on known positions are provided, a server (3) to synchronize the plural UWB transmitter-receivers (1) is provided, an RF tag (T), attached to a moving object (20) as to receive signals (I0) synchronously and periodically transmitted from the UWB transmitter-receivers (1) and reflect the signals (I0) adding inherent tag recognition signal, is provided, and the UWB transmitter-receiver (1) is composed as to obtain the distance to the moving object (20) attached with the RF tag (T) by synchronous summation and correlative calculation of the PN codes of M system reflected by the RF tag (T).