A honeycomb structure obtained by bonding, into one piece, a plurality of honeycomb segments (2) each having a plurality of passages (6) surrounded by cell walls and extending in the axial direction of the segment. In the honeycomb structure, a material A (3) having compressive elasticity is provided between a side surface (21) of at least one honeycomb segment [2(a)] not constituting the outermost peripheral surface (23) of the honeycomb structure (1) and a side surface of the honeycomb segment [(2(b)) adjacent thereto. A honeycomb structure assembly (8) obtained by providing a material B (5) having compressive elasticity on the outermost peripheral surface (23) of the honeycomb structure (1) in a compressed state and thereby compression-holding the resulting honeycomb structure in a metallic container (11). A honeycomb structure using materials having compressive elasticity (B) is resistant to breakage, and has superior durability and reliability, by reducing the thermal stress generated therein during use by a sharp temperature change of inflow gas, a local heat of reaction and a local heat of combustion.