An electronic device is provided. The electronic device includes a housing including a front plate, a rear plate facing away from the front plate, and a side structure surrounding a space between the front plate and the rear plate, a heat dissipation member accommodated inside the housing, at least one antenna module disposed adjacent to the side structure or at least partially accommodated in the side structure, the at least one antenna module being disposed to be inclined or perpendicular relative to the front plate or the rear plate, and a fixing member coupled to and at least partially surrounding the antenna module. The fixing member may include a first heat transfer portion at least partially surrounding a rear face of the antenna module, and a second heat transfer portion disposed in contact with the heat dissipation member.