An antenna array device provided, which includes a substrate, multiple antenna elements, a metal ground plate and a first isolation unit group. The multiple antenna elements are disposed on a first surface of the substrate. The multiple antenna elements have a first polarization direction and a second polarization direction opposite to the first polarization direction. The first isolation unit group is disposed between adjacent two of the multiple antenna elements. An arrangement direction of the first isolation unit group is perpendicular to the first polarization direction and the second polarization direction. The first isolation unit group is two isolation units which are adjacent, each of which comprises an outer end and an inner end opposite to the outer end. The inner end is connected to the metal ground plate disposed on a second surface of the substrate via a second via.