HONEYCOMB STRUCTURE

The present invention provides a honeycomb structure capable of mitigating stress concentration occurring in the vicinity of a boundary wall and suppressing a decrease in mechanical strength. The honeycomb structure is provided with a honeycomb structure; a columnar honeycomb structure part (4) having porous partition walls (1) that define a plurality of cells (2); the honeycomb structure part (4)is composed of a central part (15) and an outer peripheral part (16). The compartment (2) is triangular or hexagonal; the shape of the compartment (2a) formed in the central section (15) and the shape of the compartment (2b) formed in the outer peripheral section (16) are congruent or similar. In the shape of the cells (2), the number of axes of symmetry is A, the number of vertices of the shapeof the cells (2) is N, the value indicated by formula (1) is theta, and the arrangement direction of the cells (2b) in the outer peripheral section (16) is inclined within the range of theta-15 DEG totheta + 15 DEG with respec