An antenna device includes a first insulating base portion including a spiral antenna pattern, and a second insulating base portion including at least two conductor wires. An insulating layer configured to insulate the conductor wires from the antenna pattern is provided between a first end and a second end of the antenna pattern in a planar view. The insulating layer includes a cut or an opening allowing at least one of the first end and the second end of the antenna pattern to be exposed toward the conductor wires. Electrode portions of the conductor wires are electrically and mechanically connected to the first end and the second end, respectively, of the antenna pattern by a conductive material in the cut or the opening of the insulating layer. The second insulating base portion is more flexible than the first insulating base portion.