A honeycomb structure includes a honeycomb substrate including latticed partition walls which define a plurality of cells extending from one end face to the other end face and forming through channels for fluid and a honeycomb outer wall, and a flange portion attached to a part of the honeycomb outer wall of the honeycomb substrate, and including latticed flange partition walls which define a plurality of flange cells extending from one flange end face to the other flange end face and a flange outer wall, and in the honeycomb substrate, a ratio of a non-outer wall region in which the honeycomb outer wall is not disposed is in a range of 10 to 90% to a total area of a substrate circumferential surface.