An antenna element (3) has an upstanding section (3a) erected from a base member (2); a tuning section (3b) extended from the upper end of the upstanding section (3a) into one direction in a parallel plane parallel to the base member (2), bent in the middle, and then extended in the direction opposite the one direction; and an open element section (3c) extended from the front end of the tuning section (3b) in the direction in which the open element section (3c) spirally turns in the parallel plane about the upstanding section (3a).
