An electronic device and an antenna device are provided herein. An electronic device includes a conductive sidewall; a conductive structure located within a space formed by the conductive sidewall and extending from the conductive sidewall, wherein the conductive structure includes a first surface directed toward a front of the portable electronic device and a second surface directed toward a back of the portable electronic device; a non-conductive structure located within the space formed by the conductive sidewall and contacting the conductive structure, wherein the non-conductive structure includes a first surface directed toward the front of the portable electronic device and a second surface directed toward the back of the portable electronic device; an antenna pattern electrically connected to the conductive structure; and a flexible conductive connector electrically connected to the conductive structure and the antenna pattern. The antenna pattern extends on a portion of the first surface of the conductive structure and on a portion of the first surface of the non-conductive structure, or extends on a portion of the second surface of the conductive structure and on a portion of the second surface of the non-conductive structure.