To provide an improved antenna element, array antenna, communication unit, mobile body, and base station. The antenna element includes: a conductor part; a ground conductor; a first predetermined number of connection conductors, the first predetermined number being three or more; a first feeding line; a second feeding line; and a filter. The conductor part extends along a first plane and includes a plurality of first conductors. The ground conductor is positioned separately from the conductor part and extends along the first plane. The connection conductor extends from the ground conductor toward the conductor part. The first feeding line is configured to be electromagnetically connected to the conductor part. The second feeding line is configured to be electromagnetically connected to the conductor part at a position different from that of the first feeding line. The filter is configured to be electrically connected to at least one of the first feeding line and the second feeding line. The filter is positioned to be overlapped with the ground conductor.