An antenna device includes line-shaped feeding conductors arranged so as to face each patch antenna array and performing electromagnetic coupling feeding on each of the patch antennas, from a wiring-side feeding portions formed at a position intersecting a slot when viewed from the normal direction of a first surface. The patch antennas include an electrode which is arranged so as to face the wiring-side feeding portion, between two radiation elements arranged apart in the first direction, and is electromagnetically coupled from the wiring-side feeding portion. The electrode and each of the two radiation elements are electrically coupled in the first direction.