An electronic device and a method of performing power backoff for an array antenna including a plurality of antenna elements are provided. The electronic device includes an array antenna including a plurality of antenna elements arranged to perform beamforming, a proximity detecting device configured to detect a proximity of an object, a memory, and a processor, wherein the memory is configured to store instructions that, when executed, cause the processor to communicate with an external electronic device through a first beam formed using the plurality of antenna elements and deactivate at least one of the plurality of antenna elements when the proximity of the object is detected by the proximity detecting device during communication with the external electronic device.