To obtain a PHS device and a present location transducer for a navigation system capable of reliably detecting one' own position even if radio waves are in an adverse state.

A PHS device 12 reads data from the database of an external storage device 17 which stores information on the base station locations of base station numbers and collates the position of a base station number with which the PHS device can perform transmission and reception at present with the data by an arithmetic processing unit 16 to detect a present position. In addition, by applying the present position detection function to a navigation system, it is possible to detect a present location instead of a GPS device when the navigation system can not receive GPS radio waves.