A communication apparatus is provided. A retaining wall structure electrically connected with a ground plane is disposed between a main circuit board and an antenna. A retaining wall part of the retaining wall structure has a thickness. A distance between the retaining wall part and the main circuit board is a first distance, and a distance between the retaining wall part and the antenna and is a second distance. A distance between the retaining wall and a shielding metal plate is a third distance. The projection of the antenna projected toward the retaining wall in the orthogonal projection direction falls on the retaining wall part.