There is provided a honeycomb structure comprising a plurality of honeycomb segments having porous partition walls separating and forming a plurality of cells and an outer peripheral wall located in the outermost periphery, first cells each open in an end portion on one side and plugged in the other end portion on the other side and second cells each plugged in the end portion on the one side and open in the other end portion on the other side being alternately disposed with the first cells having an area larger than that of the second cells in a cross section perpendicular to the central axial direction, and the outer peripheral wall having protruding portions along an external shape of the first cells and depressed portions along an external shape of the second cells. The honeycomb segments are bonded to each other with a bonding member.