To provide a directional antenna system that easily calculates a correction value used to correct a phase difference and an amplitude difference and that uses the calculated correction value to correct the phase difference and the amplitude difference of each element with high accuracy.

The directional antenna system is provided with a reference signal generating means 24 that generates a reference signal, switch means 25a-25d that are used to pass one of received signals from antenna elements 11a-11d to a corresponding reception system, a frequency up-converter 21 that converts a frequency of an output signal from an adder means 19 into the original frequency of the received signal, a comparison means 26 that compares an output signal from the converter with the reference signal from the reference signal generating means, an error signal generating means 27 that receives an output of the comparison means to generate an error signal, and a weighting correction means 28 that calculates a correction value to correct a weighting value corresponding to the error signal from the error signal generating means so as to sequentially calibrate each weighting value of a weighting means in a way that the error in the phase and the amplitude of the output signal from the frequency up-converter is equal to that of the reference signal.