A honeycomb core for carrying a catalyst, comprising a flat metal foil and a corrugated metal foil, the flat metal foil and the corrugated metal foil being layered, wherein the corrugated foil is configured by repeating a concavo-convex shaped part including a first top surface that is in contact with one of the flat foils adjacent in a layering direction, a second top surface that is in contact with another flat foil adjacent in the layering direction and is disposed at a position where the second top surface avoids the first top surface as viewed in the layering direction, and an inclined leg surface that has one end connected to the first top surface through a first bent part and another end connected to the second top surface through a second bent part, and extends in a direction inclined with respect to the first top surface and the second top surface, and has an offset structure having different phases of adjacent concavo-convex shaped parts between front and rear in an axial direction of the honeycomb core, the first bent part and the second bent part are each shaped to have a radius of curvature, characterized in that: the radius of curvature R1 of an inner edge of the first bent part and the radius of curvature R2 of an inner edge of the second bent part satisfy the following conditional expressions and, respectively, and a separation distance h in the layering direction between the first top surface and the second top surface and a separation distance S between a pair of the inclined leg surfaces connected to the first top surface through the first bent parts satisfy the following conditional expression: 0.02 mm ≤ R 1 ≤ 2.0 mm 0.02 mm ≤ R 2 ≤ 2.0 mm and 1.5 ≤ S / h ≤ 10 and in that a first protrusion extends from both ends in the axial direction of the first bent part toward an exhaust gas flow channel that is disposed between the first top surface and the other flat foil as viewed in the axial direction, and a second protrusion extends from both ends in the axial direction of the second bent part toward an exhaust gas flow channel that is disposed between the second top surface and the one flat foil as viewed in the axial direction. the radius of curvature R1 of an inner edge of the first bent part and the radius of curvature R2 of an inner edge of the second bent part satisfy the following conditional expressions and, respectively, and a separation distance h in the layering direction between the first top surface and the second top surface and a separation distance S between a pair of the inclined leg surfaces connected to the first top surface through the first bent parts satisfy the following conditional expression: 0.02 mm ≤ R 1 ≤ 2.0 mm 0.02 mm ≤ R 2 ≤ 2.0 mm and 1.5 ≤ S / h ≤ 10 and in that a first protrusion extends from both ends in the axial direction of the first bent part toward an exhaust gas flow channel that is disposed between the first top surface and the other flat foil as viewed in the axial direction, and a second protrusion extends from both ends in the axial direction of the second bent part toward an exhaust gas flow channel that is disposed between the second top surface and the one flat foil as viewed in the axial direction.