Disclosed are an electronic device and a method of transmitting a wireless signal thereof. The electronic device includes: a housing; a first antenna configured to form a first part of the housing; a second antenna configured to form a second part of the housing; and at least one processor including a first transmission terminal and a second transmission terminal connected to the first antenna and the second antenna, respectively, wherein the at least one processor is further configured to identify a strength of at least one of a transmission signal and a reception signal when transmission of a wireless signal is requested, and control at least one of a phase and a strength of wireless signals output through the first transmission terminal and the second transmission terminal according to a result of the identification. Various other embodiments are possible.