There are provided: a main receiving unit for receiving incoming signals from a base station via a main antenna provided in a portable terminal; sub receiving units for receiving incoming signals from the base station via a plurality of detection antennas provided in the portable terminal; a detection unit for detecting the arriving direction of base station signals in the radio wave environment of the portable terminal based on receiving level information of the main antenna, on receiving level information of the detection antennas and on directivity information of the detection antennas; and notifying units for notifying information about the arriving direction of the base station signals detected by the detection unit.