A honeycomb structure includes at least one honeycomb unit which includes walls. The walls have a thickness of from about 0.10 mm to about 0.50 mm and extend along a longitudinal direction of the honeycomb structure to define through-holes. The honeycomb structure has a center area inside a boundary line passing through positions located at substantially a half of a length from a center of the honeycomb structure to a periphery of the honeycomb structure in a cross section perpendicular to the longitudinal direction. The honeycomb structure has a peripheral area outside the boundary line. A thickness of the walls located in the peripheral area is larger than a thickness of the walls located in the center area. A first opening ratio in the center area in the cross section is larger than a second opening ratio in the peripheral area in the cross section.
