Patent ID: 7517502

Claim:
A pillar-shaped honeycomb structural body comprising: a porous ceramic body in which a plurality of through holes are formed in parallel with one another in a length direction of the porous body and a partition wall portion is interposed between the through holes, the porous body having an inlet side and an outlet side, wherein said plurality of through holes includes a group of inlet-side through holes sealed by plugs at the outlet side and a group of outlet-side through holes sealed by plugs at the inlet side, the inlet-side through holes have the total sum of cross section areas perpendicular to the length direction which is made relatively greater, outlet-side through holes have the total sum of cross section areas perpendicular to the length direction which is made relatively smaller, and the inlet-side through holes and the plugs sealing the inlet-side through hole at the outlet side satisfy inequalities, 0.0157 X− 0.0678 <Y< 1.15 X− 5 and 35≦X≦60, where X represents an aperture rate on the inlet side in %, and Y represents the total sum of thermal capacities in J/K of the plugs sealing the inlet-side through holes at 500° C. per 11.8 cm 2 of an end face of the ceramic body on the outlet side including the outlet-side through holes.