An antenna module includes a dielectric substrate including a plurality of dielectric layers that are laminated, and a radiation element, a ground electrode, and peripheral electrodes that are formed in or on the dielectric substrate. The radiation element radiates radio waves in a first polarization direction. The ground electrode is placed so as to face the radiation element. The peripheral electrodes are formed in a plurality of layers between the radiation element and the ground electrode and are electrically connected to the ground electrode. The peripheral electrodes are placed at positions that are symmetrical with respect to at least either of a first direction parallel to the first polarization direction and a second direction orthogonal to the first polarization direction.