An antenna assembly and an antenna device including the same are provided. The antenna assembly includes antenna elements, a first printed circuit board (PCB), cavity filters, and a second PCB. The first PCB has one surface provided with the antenna elements. The cavity filters are installed on the other surface of the first PCB and electrically connected to the plurality of antenna elements. The second PCB has one surface electrically connected to the cavity filters and includes at least a power amplifier, digital processing circuit, and calibration network. The second PCB includes one or more first processing areas and one or more second processing areas extending in parallel with each other. The digital processing circuit is disposed in the second processing area and not in the first processing area. The power amplifier is disposed in the first processing area and not in the second processing area.