A honeycomb structural body includes a plurality of honeycomb units, first and second electrodes, and first and second conductive members. The plurality of honeycomb units are adhered to each other by interposing an adhesive layer. Each of the plurality of honeycomb units contains a conductive ceramic material. Each of the plurality of honeycomb units includes cell walls extending along a longitudinal direction of each of the plurality of honeycomb units to define a plurality of through-holes. The first and second electrodes are provided on an outer peripheral surface of each of the plurality of honeycomb units. The first and second conductive members are electrically connected to the first and second electrodes, respectively.