A honeycomb structure having a structure wherein a honeycomb segment bonding body (10) integrally bonding a plurality of honeycomb segments (2) on mutual bonding surfaces through bonding material layers (9) is provided and a plurality of cells (5) to be flow paths of a fluid are arranged in parallel in a center axis direction. The porosity of an outer side portion of the bonding material layer (9), which is a portion from an interface with a bonding surface of the honeycomb segment to an area at a distance equivalent to 20% of the entire layer thickness, is smaller than the porosity of a center portion positioned inside the outer side portion.
