A honeycomb structure is provided that includes a plurality of pillar-shaped honeycomb fired bodies, each having a number of cells longitudinally disposed in parallel with one another with a cell wall therebetween. An adhesive layer is interposed between adjacent honeycomb fired bodies of the plurality of honeycomb fired bodies to combine the plurality of honeycomb fired bodies together, and a sealing material layer is formed on an outer peripheral face of the combined plurality of honeycomb fired bodies. At least two honeycomb fired bodies of the plurality of honeycomb fired bodies have an outer wall that forms a portion of the outer peripheral face of the combined plurality of honeycomb fired bodies. At least one of the outer walls has a protruding portion extending from a surface thereof, and the protruding portion is made from a same material as a material of the at least one outer wall.