In a mobile communication system, the movement of the terminal must be considered, and the positional information of the terminal must be retained so that the terminal can be communicated with after movement. In a radio communication system composed only of terminals, the terminals do not form a hierarchy, and it is difficult to acquire the position informations around the terminal in real time, if a facility or a terminal does not exist for centralized management of positional information. This paper presents a procedure for secure and efficient routing, where the positional information of the terminal is acquired at an arbitrary time and is utilized differently according to the elapsed time from its generation to its use. The usefulness of the approach is shown by an approximate analysis and a computer simulation. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(6): 68–77, 2000