An antenna device includes first and second dielectric layers. The first dielectric layer includes first and second sides facing each other in a third direction. The second dielectric layer includes third and fourth sides facing each other in the third direction. A first antenna patch is disposed on the first side of the first dielectric layer. A second antenna patch is disposed on the third side of the second dielectric layer. Signals with a first frequency bandwidth are transmitted or received electrical signals applied to the first antenna patch. Signals with a different second frequency bandwidth are transmitted or received by an electrical signal applied to the second antenna patch. A height of the second dielectric layer measured to the third side from the fourth side in a direction parallel to a third direction is greater than a height of the first dielectric layer measured to the first side from the second side.