A plate-shaped radiating element of a shape having at least three planes is formed by bending a metal plate having a substantially rectangular shape. A first slit is provided from a lower edge of the plate-shaped radiating element up to a portion in the vicinity of an upper edge of the plate-shaped radiating element while passing through a center point of the plate-shaped radiating element, and forms plate-shaped dipole elements on both sides thereof. A second slit is provided parallel to the upper edge of the plate-shaped radiating element and forms a folded element on an upper side thereof. Feeding points are provided on both sides of the first slit at the lower edge of the plate-shaped radiating element.