A honeycomb structural body of the present invention includes plural honeycomb units adhered to each other by interposing an adhesive layer, each of the plural honeycomb units having a plurality of through-holes arranged in a longitudinal direction thereof and containing a conductive ceramic material. The honeycomb structural body has a circular-pillar shape or an elliptical-pillar shape. The honeycomb unit has a fan-like shaped or an elliptical fan-like shaped cross section perpendicular to the longitudinal direction. A pair of electrodes is formed at a part of an outer peripheral surface of the honeycomb unit that does not face the adhesive layer and an area between the honeycomb unit and the adhesive layer and/or formed at an area between the outer peripheral surface of the honeycomb unit and the adhesive layer and an area including a center of the fan-like shaped or the elliptical fan-like shaped cross section perpendicular to the longitudinal direction.