Honeycomb structure

A honeycomb structure comprising:

• a pillar-shaped honeycomb structure body having a porous partition wall disposed so as to surround a plurality of cells which serve as fluid through channels extending from a first end face to a second end face;
• and a circumferential wall disposed so as to encompass the partition wall, wherein
• in a section orthogonal to the extending direction of the cells of the honeycomb structure body, the shape of the cell is a polygonal shape with a corner having an arc shape,
• a thickness T1[mm] of the partition wall is 0.0500 to 0.1400 mm,
• a radius of curvature R1[mm] of the corner having the arc shape of the cell and the thickness T1[mm] of the partition wall satisfy the relationship of Equation (1),
• in the section orthogonal to the extending direction of the cells of the honeycomb structure body, the outer diameter of the honeycomb structure body is 190.5 to 355.6 mm, and
• a porosity of the partition wall is 20 to 40%.
• 0.0050≤R1×T1≤0.0150 Equation (1):