An electronic device is provided. The device includes a housing including a first cover having a first dielectric constant, and an antenna structure disposed in an inner space of the housing. The antenna structure may include a PCB, an antenna element disposed in the PCB to form a beam pattern in a specific direction, a first dielectric structure disposed on a radiation path of the beam pattern, formed integrally with or combined with the PCB, and having a second dielectric constant equal to or different from the first dielectric constant, and a second dielectric structure disposed on the radiation path between the first dielectric structure and the first cover, and having a third dielectric constant higher than the first dielectric constant and the second dielectric constant. The electronic device may further include a wireless communication circuit configured to transmit and/or receive a radio signal through the antenna element.