PURPOSE: To save a trouble for reporting and writing a position regarding a mobile body, and enable the bearing and distance of a partner mobile body to be accurately measured by displaying the positions of own and other mobile bodies on the basis of positional information regarding both mobile bodies.

CONSTITUTION: GPS receiving section 11 obtains the position of an own mobile body (own machine) at the latitude and longitude on the basis of signals sent from selected three to four GPS satellites at the predetermined time intervals, and transmits the data of the position as positional information regarding the own machine to a bidirectional communication section 12 and a bearing and distance calculation section 13. A communication section 12 is normally engaged in two-station communication with GPS transceiver for the other mobile body (other machine) via an aural signal. Upon receipt of information regarding the own position from the receiving section 11, therefore, the communication section 12 transmits an aural signal and positional information regarding the own machine to the specific other machine. Also, signals from the other machine are separated into an aural signal and positional information regarding the other machine, and inputted to the calculation section 13. Furthermore, the bearing and distance of the other machine viewed from the own position are obtained on the basis of the information regarding the own and other machines, and signals representing the position, bearing and distance of both machines are sent to a display 14 for indication together with map information.