| abstract |
A honeycomb structure in which cells have a hexagonal cross-sectional shape, and cells having openings in the range of 1-80% of the area of a first end face of a honeycomb structure section are specific open cells having an opening variation only in the range of 30mm or less from the first end face, wherein the diameter D2 of an inscribed circle in a second end face of the cells, which is in contact with the peripheral edge of the opening, and the diameter D1 of an inscribed circle in the first end face of the cells, which is in contact with the peripheral edge of the opening, satisfy the relationship of 1 ≦ 1- (D1/D2)) × | < 70 for the opening variation, and the diameter D2 of an inscribed circle in a second end face of the cells, which is in contact with the peripheral edge of the opening, and the diameter D5636 of an inscribed circle in a cross-section orthogonal to the direction from the first end face toward the second end face satisfy the relationship of 1 ≦ 1 | (D1/D3)) of 1 ≦ 70. |