An antenna apparatus is provided which has a centroid close to a vibration isolation structure and which is hard to vibrate like a pendulum motion when vibration is applied. The antenna apparatus includes a first base plate, an antenna unit disposed at a side of the first base plate and supported by the first base plate, and a counter weight unit disposed at another side of the first base plate opposite to the antenna unit and supported by the first base plate. The antenna apparatus further includes a vibration isolation structure having one end fixed to the first base plate to suppress a vibration of the first base plate, and a second base plate to which other end of the vibration isolation structure is fixed and which is fixed to a moving object or a structural object.