A honeycomb structure comprising (100, 110, 120, 130, 140): a pillar-shaped honeycomb structure body having porous partition walls defining and forming a plurality of cells which extend from one end face to the other end face and become through channels for a fluid, and a circumferential wall positioned at an outermost circumference; and a pair of electrode members disposed on a side surface of the honeycomb structure body, wherein an electric resistivity of the honeycomb structure body is from 0.01 to 2 Ωm, each of the pair of electrode members is formed into a band shape extending in a cell extending direction of the honeycomb structure body, in a cross section orthogonal to the cell extending direction, one electrode member in the pair of electrode members is disposed on a side opposite to the other electrode member in the pair of electrode members via a center of the honeycomb structure body, in the honeycomb structure body, one or more slits each having an open end in the side surface are formed, at least one of the slits is a specific slit having a first region which is a region extending in the same direction as an extending direction of the slit from the open end at a width equal to a width of the open end of the slit and second regions (17, 17a, 17b) which are regions adjacent to the first region in a width direction in the cross section orthogonal to the cell extending direction, a length of at least a part of the second region (17, 17a, 17b) in a direction orthogonal to the slit extending direction is a length which is not less than a length of a half of a width of the cell, a charging material is charged into the specific slit, and the charging material has a first region charging portion charged into the first region in a space constituting the specific slit, and second region charging portions charged into the second regions (17, 17a, 17b), at least one of the second region charging portions is an effective second region charging portion, and a length of the effective second region charging portion in the direction orthogonal to the slit extending direction is a length which is not less than the length of the half of the width of the cell in the cross section orthogonal to the cell extending direction; wherein the effective second region charging portion is constituted by at least a part of the charging material charged in an outermost circumference cell that is the cell positioned at the outermost circumference among the cells defined and formed only by the partition walls. a pillar-shaped honeycomb structure body having porous partition walls defining and forming a plurality of cells which extend from one end face to the other end face and become through channels for a fluid, and a circumferential wall positioned at an outermost circumference; and a pair of electrode members disposed on a side surface of the honeycomb structure body, wherein an electric resistivity of the honeycomb structure body is from 0.01 to 2 Ωm, each of the pair of electrode members is formed into a band shape extending in a cell extending direction of the honeycomb structure body, in a cross section orthogonal to the cell extending direction, one electrode member in the pair of electrode members is disposed on a side opposite to the other electrode member in the pair of electrode members via a center of the honeycomb structure body, in the honeycomb structure body, one or more slits each having an open end in the side surface are formed, at least one of the slits is a specific slit having a first region which is a region extending in the same direction as an extending direction of the slit from the open end at a width equal to a width of the open end of the slit and second regions (17, 17a, 17b) which are regions adjacent to the first region in a width direction in the cross section orthogonal to the cell extending direction, a length of at least a part of the second region (17, 17a, 17b) in a direction orthogonal to the slit extending direction is a length which is not less than a length of a half of a width of the cell, a charging material is charged into the specific slit, and the charging material has a first region charging portion charged into the first region in a space constituting the specific slit, and second region charging portions charged into the second regions (17, 17a, 17b), at least one of the second region charging portions is an effective second region charging portion, and a length of the effective second region charging portion in the direction orthogonal to the slit extending direction is a length which is not less than the length of the half of the width of the cell in the cross section orthogonal to the cell extending direction; wherein the effective second region charging portion is constituted by at least a part of the charging material charged in an outermost circumference cell that is the cell positioned at the outermost circumference among the cells defined and formed only by the partition walls.