A honeycomb structure constituted by honeycomb segments, where a honeycomb segment has a first end and second end surfaces of a quadrangular shape; the second end surface having an area larger than that of the first one, a first pair of two side surfaces facing each other in parallel, and a second pair of two side surfaces facing each other make side surfaces become gradually narrow from the second end surface toward the first end surface, where a plurality of honeycomb segments are disposed in such a manner that the honeycomb segments are aligned to form rows in parallel in a predetermined direction, so as to make adjacent honeycomb segments directed opposite to each other in first end surfaces bonded to each other with one of side surfaces of the second pair of side surfaces.