A positioning system using a mobile Internet signal is disclosed. The positioning system includes access points for transmitting downlink signals for mobile Internet communications, an access terminal for generating positioning information using the downlink signals received from the access points and access point information on the access points, and a position determination entity (PDE) for calculating range values between the access terminal and the access points using the positioning information from the access terminal and determining a position of the access terminal using the range values. Since the positioning system determines the position using the mobile Internet signal, an accurate terminal position can be determined even in such environments as downtown, shaded and indoor areas.