Abstract: A conductive honeycomb structure that is divided into four equal portions in a flow path direction of cells in the structure to form four regions of A, B, C, and D from a side closer to a first end face, and an average value of electric resistances measured between two points in each of the four regions is represented as RA, RB, RC, and RD in this order from the side closer to the first end face. A relational expression of RA?RB?RC?RD (excluding RA=RB=RC=RD) is satisfied provided that the two points being determined so that a distance between a pair of electrode layers arranged on an outer peripheral side wall of the structure is the longest in the cross section perpendicular to the flow path direction of the cells.

Abstract: A conductive honeycomb structure that is divided into four equal portions in a flow path direction of cells in the structure to form four regions of A, B, C, and D from a side closer to a first end face, and an average value of electric resistances measured between two points in each of the four regions is represented as RA, RB, RC, and RD in this order from the side closer to the first end face. A relational expression of RA?RB?RC?RD (excluding RA=RB=RC=RD) is satisfied provided that the two points being determined so that a distance between a pair of electrode layers arranged on an outer peripheral side wall of the structure is the longest in the cross section perpendicular to the flow path direction of the cells.