A received electric field intensity estimates device estimaties a received electric field intensity when a signal is received, by using at least a gain in a transmitting direction indicating the direction of the receiver viewed from a transmitter's side from among gains in the individual directions of the antenna's directive pattern of a transmitter's antenna, and outputs the estimated intensity. The device includes: an averaging unit for averaging gains in the individual directions of the antenna's directive pattern within an angular range of an arrival wave angle indicating the direction of the signal arriving at the receiver, taken as the relevant direction; and a received electric field intensity calculation unit using at least the gain in the transmitting direction from among gains in the individual directions of the antenna's averaged directive pattern, and for outputting the result of the calculation as the estimated received electric field intensity.