An antenna device includes a ground plane; a first resonator extending in a direction at a distance from the ground plane and connected to a feeding point; and a second resonator arranged at a distance from the first resonator. The ground plane includes an edge portion formed along the second resonator, with a resonance current being formed on the first resonator and the ground plane. The second resonator is configured to function as a radiation conductor by resonance of the first resonator. A tip portion of the first resonator is located near a metallic part. The second resonator has a plurality of electrical lengths of differing resonance frequencies.