The present invention is to provide an antenna device with the isolation among feedpoints being further improved. In order to achieve this goal, the present invention provides an antenna device provided with a substrate having a ground area, and a first conductor, a second conductor and a third conductor. In the antenna, one end of the second conductor is connected to the ground area via a first feedpoint and the other end of the second conductor is connected to the first conductor. A second feedpoint is included serially in the third conductor at any position. Further, at least part of the third conductor is disposed opposite to the first conductor, and both ends of the third conductor are connected to the ground area.