Electronic device including antenna and stylus pen

An electronic device including an antenna and a stylus pen, that can reduce antenna performance degradation, is provided. The electronic device includes a housing including a conductive part and at least one cut-off portion formed in the conductive part, a printed circuit board disposed inside the housing, a wireless communication interface disposed on the printed circuit board, and a stylus pen, wherein the conductive part may be electrically connected to the wireless communication interface, wherein the stylus pen may include at least one cut-off portion, and at least one magnet enabling attachment and detachment to and from the housing, and wherein when the stylus pen is attached to the housing, the at least one cut-off portion formed in the conductive part and the at least one cut-off portion formed in the stylus pen are aligned.