An antenna array device and an antenna unit thereof are provided. The antenna unit includes a support and an antenna structure. The support is integrally formed as a single one-piece structure, and has a substrate, a first stand, and a second stand. The first stand and the second stand extend from two opposite sides of the substrate, respectively. The substrate and at least one of the first stand and the second stand jointly define a plurality of cavities. The antenna structure includes a plurality of patches that are formed on the substrate and that are arranged in the cavities.