An antenna apparatus includes: first and second receiving antennas disposed on a plane at equal distances from a reference point and face each other with the reference point therebetween; third and fourth receiving antennas disposed on the plane, a gravity center of the third and fourth receiving antennas being an equal distance from the reference point, a straight line connecting the gravity centers of the third and fourth receiving antennas is at 90 degrees with respect to a straight line connecting gravity centers of the first and second receiving antennas; fifth, sixth, seventh and eighth receiving antennas disposed on the plane, having gravity centers on straight lines different from each other and rotated by an angle of 45 degrees from the straight line connecting the gravity centers of the first and second receiving antennas and the straight line connecting the gravity centers of the third and fourth receiving antennas, respectively.