An electronic device including an antenna and a conductive pattern formed around the antenna is provided. The electronic device includes a housing including a first plate, a second plate facing away from the first plate, and a side member surrounding a space between the first plate and the second plate, connected to the second plate or integrally formed with the second plate, and including a conductive material, an injection-molding material disposed in the space between the first plate and the second plate in the housing and formed of a non-conductive material, an antenna module including conductive radiators and supported by the injection-molding material, and a conductive pattern disposed on a first surface adjacent to the second plate of the injection-molding material or disposed inside the injection-molding material and disposed adjacent to a part of an edge of the antenna module corresponding to a boundary between the antenna module and the injection-molding material when viewed from the second plate in a direction of the first plate. A partial conductive radiator of the conductive radiators may be disposed to transmit and/or receive a signal through the second plate.