Honeycomb structure

A honeycomb structure comprising a pillar-shaped honeycomb structure body having a first end and a second end face, wherein

• the honeycomb structure body includes:
• porous partition walls disposed so as to surround a plurality of cells extending from the first end face to the second end face;
• and a circumferential wall disposed to surround the partition walls,
• the honeycomb structure body has a cross section orthogonal to the extending direction of the cells where the partition walls define the cells to have a polygonal shape in a grid pattern,
• the honeycomb structure body has at least one missing part at an end-face edge where the first end face or the second end face intersects the circumferential wall, the missing part missing a part of the circumferential wall and the partition walls,
• the missing part is disposed at least at one position having polar coordinates (R, θ) on the first end face or the second end face that makes up the end-face edge, the θ satisfying the value of θ(n=1,2 . . . N) in the following condition (1),
• the average size of the missing part is such that the radial length on the end face of the honeycomb structure body is 0.8 to 8.0 mm, the perimeter along the rim of the end face of the honeycomb structure body is 0.8 to 41.0 mm, and the axial length in the extending direction of the cells of the honeycomb structure body is 0.1 to 32.0 mm, and
• a percentage of a ratio of total area of the missing part on the lateral face of the honeycomb structure body to total area of the lateral face of the honeycomb structure body is 1.40% or less.
• (Math. 1)
• θ(n=1, 2 . . . N)={(π/N)+(2π/N)×(n−1)}(±θ(where n=1)/2) Condition (1)
• where R in the polar coordinates (R, θ) indicates a radial coordinate that represents the radius of the first end face or the second end face that makes up the end-face edge of the honeycomb structure body,
• θ in the above polar coordinates (R, θ) indicates an angular coordinate having, as 0, the intersection on the first end face or the second end face where the rim of the end face intersects a line that is parallel to the grid-like aligned partition wall and passing through the center of the end face, and
• in the condition (1), N denotes the number of apexes of the polygonal cell, where N=4 to 8, and n denotes a natural number of N or less (n=1, 2 . . . N).