The present invention relates to a method for performing beamforming by using circular array antenna comprising a plurality of antennas, and a device therefor, and to a method and a device therefor, the method comprising the steps of: determining the number of operating antennas for a specific beam pattern; selecting at least one antenna among the plurality of antennas by using the determined number of operating antennas; and transmitting a signal through the selected at least one antenna, wherein the step of determining the number of operating antennas determines the number of operating antennas by using the inverse number of the square of the vertical beam width of the specific beam pattern.