Disclosed herein is an antenna device that includes a first coil pattern having at least first, second, and third turns. As viewed in a coil axis direction, each of the first, second, and third turns has an opening with a width larger in a first direction than in a second direction orthogonal to the first direction. The width of the opening of the second turn in the second direction is larger than a width of the opening of the first turn in the second direction. The width of the opening of the third turn in the second direction is larger than the width of the opening of the second turn in the second direction and smaller than a width of the opening of the first turn in the first direction.