Patent ID: 7785695

Claim:
A pillar-shaped honeycomb structured body, comprising: a plurality of large-capacity through holes and a plurality of small-capacity through holes; a first partition wall between two adjacent large-capacity through holes; a second partition wall between a large-capacity through holes and a small-capacity through holes adjacent to each other, a first end face and a second end face, wherein each of the plurality of large-capacity through holes and small-capacity through holes extends from the first end face to the second end face, wherein a large-capacity through hole is sealed at the first end face and a small-capacity through hole is sealed at the second end face, wherein an aperture rate α (%) is a ratio between the sum of the area of the large-capacity through holes at the second end face and the area of the second end face, wherein the difference in the thickness of the first partition wall and the second partition wall is β (mm), wherein α and β satisfy the following inequalities (1) and (2): 0.0022α+0.0329≦β≦0.0071α+0.2553 (1), and about 35≦α≦about 60 (2).