A first plate-like radiating element including a first side and a second side, the first side being a straight line portion and the second side being curved; and a second plate-like radiating element including a third side and a fourth side, the third side being a straight line portion and the fourth side being curved, are included. The first side of the first radiating element and the third side of the second radiating element are disposed to face each other in parallel and to be shifted in a parallel direction. The second side and the fourth side each preferably include a curve portion. The second side or the fourth side or the second and fourth sides is (are) preferably formed by a combination of one or a plurality of curve portions and one or a plurality of straight line portions.