An electronic device is provided. The electronic device includes a first housing structure including a first side surface member, a second housing structure including a second side surface member, a hinge structure configured to rotatably connect the first housing structure and the second housing structure and configured to provide a folding axis on which the first housing structure and the second housing structure rotate, and at least one printed circuit board, wherein the first side surface member or the second side surface member includes a first side surface portion a second side surface portion, a third side surface portion, a fourth side surface portion, a fifth side surface portion, a first slit a second slit a third slit, and a fourth slit, and a fifth slit, and wherein at least part of at least one of the second side surface portion, the third side surface portion, and the fourth side surface portion is formed of a radiation conductor and is electrically connected to the at least one printed circuit board.