An antenna device according to the present disclosure includes a first antenna that is oriented in a first direction and transmits and receives a signal with a first polarization, a second antenna that is oriented in a second direction opposite to the first direction and transmits and receives a signal with the first polarization, a third antenna that is oriented in a third direction and transmits and receives a signal with a second polarization, a fourth antenna that is oriented in a fourth direction opposite to the third direction and transmits and receives a signal with the second polarization. The second antenna is provided with a feeding point placed in phase with a feeding point of the first antenna. The fourth antenna is provided with a feeding point placed in opposite phase to a feeding point of the third antenna.