An antenna device comprising a first antenna, a second antenna and a circuit board. The first antenna includes a first insulating layer, a first signal-feeding line and two first grounding lines. The first signal-feeding line is disposed on a first surface of the first insulating layer. The first grounding lines are disposed on a second surface of the first insulating layer. The second antenna includes a second insulating layer, a second signal-feeding line and two second grounding lines. The second signal-feeding line is disposed on a first surface of the second insulating layer. The second grounding lines are disposed on a second surface of the second insulating layer. The first insulating layer and the second insulating layer intersect at about 90 degrees. The first and second antennas are disposed on a first surface of the circuit board. The first axis and the second axis are adjacent and substantially parallel.