A communication apparatus communicating other apparatuses includes: a switch for switching between a vertical polarized antenna and a horizontal polarized antenna; a communication device for transmitting and receiving the electric wave via one of the antennas, which is selected by the switch; a monitor for monitoring a relative distance between the apparatus and other apparatuses; and a controller for controlling the switch such that the switch selects the vertical polarized antenna when the relative distance is equal to or larger than a distance threshold, and the switch selects the horizontal polarized antenna when the relative distance is smaller than the distance threshold. The distance threshold is larger than a distance between the apparatus and a dip point.