Patent ID: 7348049

Claim:
A honeycomb structural body comprising: a pillar-shaped ceramic block made of porous ceramic which includes a number of through holes that are placed in parallel with one another in the length direction with a wall portion interposed therebetween; and a sealing material provided on an outer peripheral portion of said pillar-shaped ceramic block, each of said honeycomb structural body and said pillar-shaped ceramic block having irregularities formed on an outer peripheral face thereof wherein: when a least square curve is determined by a least square method on the basis of points constituting the contour of a cross-section perpendicular to the length direction of said honeycomb structural body, a center-of-gravity thereof is defined as c 1 , a distance between a minimum concentric circumscribed curve, having c 1 as the center-of-gravity, of said least square curve and the center-of-gravity c 1 is defined as D 1 , a distance between a maximum concentric inscribed curve, having c 1 as the center-of-gravity, of said least square curve and the center-of-gravity c 1 is defined as D 2 , and (D 1 -D 2 ) is defined as M 1 , the following inequality is satisfied: about 0.3 mm≦M 1 ; and when a least square curve is determined by a least square method on the basis of points constituting the contour of a cross-section perpendicular to the length direction of said ceramic block, a center-of-gravity thereof is defined as c 2 , a distance between a minimum concentric circumscribed curve, having c 2 as the center-of-gravity, of said least square curve and the center-of-gravity c 2 is defined as D 3 , a distance between a maximum concentric inscribed curve, having c 2 as the center-of-gravity, of said least square curve and the center-of-gravity c 2 is defined as D 4 , and (D 3 -D 4 ) is defined as M 2 , the following inequality is satisfied: about 0.5 mm≦M 2 ≦7.0 mm.