BIOLOGICAL ELECTRODE

A biological electrode that includes an electrode member made of a conductive rubber having a plurality of electrode portions in contact with a body of a subject. The plurality of electrode portions are protrusively formed on an electrode portion forming surface of the electrode member and arranged circularly or concentrically on the electrode portion forming surface. Further, each of the plurality of electrode portions is formed so that a cross-sectional area thereof gradually decreases from a proximal end portion thereof toward a distal end portion thereof and a center of a cross section of the distal end portion is positioned radially outward of a center of a cross section of the proximal end portion as viewed from an arrangement center of the plurality of electrode portions.