An antenna apparatus includes a ground plane having a rectangular shape in plan view, and four inverted F antenna elements configured to be placed on a surface of the ground plane and to be arranged in a symmetrical manner with respect to the central point of the ground plane in plan view, wherein each of the four inverted F antenna elements includes a short strip extending from one end of a main strip to the short end, a feeding strip, an open strip configured to extend toward the open end from the other end of the main strip to a position placed at a second height lower than the first height, and an end strip configured to extend from a distal end of the open strip to the open end and placed parallel to the ground plane at the second height.