A position detection method employed in a position detection system for detecting the position of a terminal of a radio communication system is provided which determines propagation times of a signal between the terminal and a plurality of access points located around the terminal by the principle of trilateration, thus permitting reduction in position detection time. The invention comprises means for determining a movement velocity of the terminal from a temporal history of positional information about the terminal obtained by position detection with the trilateration, means for grouping the terminals with low relative velocities based on the terminal movement velocities, a control database including the terminal position information, the terminal movement velocities, and the group information as components, and means for determining a detection cycle of the terminal of interest for position detection using the control database. A representative terminal of the terminals grouped is subjected to a position detection procedure by sending a transmit signal for the position detection, while the terminal other than the representative terminal of the group has its position estimated by its relative velocity, thereby permitting reduction in the position detection time per terminal.