A honeycomb structure includes a ceramic block including a plurality of honeycomb fired bodies. Each of the plurality of honeycomb fired bodies includes large volume cells and small volume cells. Either one of the end portions of each of the large volume cells and the small volume cells is plugged. An aperture in the cross section in a central part of the honeycomb structure is about 65% or more. A ratio of an aperture of the first end face to an aperture of the second end face of the honeycomb structure is about 1.4 or more. Each of the cell walls except the peripheral walls has a thickness of about 0.1 mm to about 0.2 mm. The honeycomb structure has a diameter of about 200 mm or more. A ratio of a length to the diameter of the honeycomb structure is about 1.0 or less.