The present invention aims to provide a honeycomb structure capable of preventing a plugging failure and forming cracks by heat shock which are caused by a cell having a small cross-section. The present invention is a honeycomb structure used for a filter for purifying an exhaust gas discharged from an internal combustion engine, wherein the honeycomb structure has a double structure of an outer tube and an inner tube, on the inner side of the inner tube, an inside cell partitioning wall forming an inside through-hole is provided, between the outer tube and inner tube, an outside cell partitioning wall forming an outside through-hole is provided, the inner tube and the inside cell partitioning wall form a through-hole having an irregular cross-section, and connected through-holes are formed by making at least one of the following connection patterns: the connection between a through-hole having an irregular cross-section and an outside through-hole, the through-holes sharing the inner tube, the connection between a through-hole having an irregular cross-section and another through-hole having an irregular cross-section, the through-holes sharing an inside cell partitioning wall, and the connection between a through-hole having an irregular cross-section and an inside through-hole, the through-holes sharing an inside cell partitioning wall.