An antenna apparatus is provided to include a reflection plate, a radiating element disposed on the reflection plate and including a balun and at least two radiation arms, and a feeding network including a phase shifter. The balun includes a first feeding layer, a common ground layer, and a second feeding layer disposed in sequence. The phase shifter includes a feeding member. One end of the common ground layer is electrically connected to one of the radiation arms, and the other end of the common ground layer is electrically connected to the reflection plate. One end of the first feeding layer and one end of the second feeding layer are electrically connected to another one of the radiation arms, the other end of the first feeding layer is electrically connected to the feeding member, and the feeding member and the first feeding layer are an integrated member.