Disclosed is an electronic device including a housing including a first plate facing a first direction, a second plate facing a second direction opposite to the first direction, and a lateral member surrounding a space between the first plate and the second plate, a first antenna structure disposed to be substantially parallel with the second plate in the space, and including a substrate disposed in the space, and at least one antenna element disposed on the substrate to face at least the second plate, a conductive member disposed in the space and spaced apart from the at least one antenna element by a predetermined interval when the second plate is viewed from above.