A honeycomb structure includes a ceramic block formed by combining a plurality of honeycomb fired bodies together with an adhesive layer interposed between the plurality of honeycomb fired bodies. The plurality of honeycomb fired bodies each has cell walls extending along a longitudinal direction of the honeycomb fired bodies to define cells. The honeycomb fired bodies adjacent to each other via said adhesive layer each have at least one projected portion on the opposing side faces. The projected portions formed on the honeycomb fired bodies overlap each other when seen from an end face of the honeycomb structure and the projected portions formed on the adjacent honeycomb fired bodies abut each other.