An antenna apparatus is equipped with a plurality of antennas arrayed in line. Ones of the antennas which lie at ends of the array of the antennas are referred to as end-side antennas, while the other antennas are referred to as inner antennas. The end-side antennas have a structure different from that of the inner antennas so as to decrease a difference in directionality between the antennas used as feed elements, thereby improving the accuracy in determining an arrival direction in a simple way without increasing an amount of calculation.