A honeycomb structure is disclosed that includes plural honeycomb units bonded together by using a sealing material layer, each of the honeycomb units including plural through-holes separated by plural partition walls and provided in parallel along a longitudinal direction of the honeycomb units, wherein each of the honeycomb units includes at least ceramic particles, and inorganic fibers and/or whisker, an area of a cross section of one of the honeycomb units perpendicular to the longitudinal direction of the one of the honeycomb units is greater than or equal to about 5 cm2 and less than or equal to about 50 cm2, and a circularity of the cross section of the honeycomb structure perpendicular to the longitudinal direction of the honeycomb structure is greater than or equal to about 1.0 mm and less than or equal to about 2.5 mm.