An electrode structure includes: a base material; a conductive fabric on a first surface of the base material; and one or more conductive wires on a second surface of the base material so as to be electrically insulated from the conductive fabric. The second surface is opposite to the first surface of the base material. The base material includes: a first area and a second area. The first area is fitted into a groove of the rim and the second area is placed in a part of a rim of a steering wheel other than the groove, when the base material is attached to the rim. The one or more conductive wires are arranged at a lower wiring density in the first area than in the second area.