Heat exchanger and water heating device comprising same

The invention provides a heat exchanger and a hot water device comprising the same, wherein the heat exchanger can appropriately prevent the temperature of a side wall part of a shell from becoming very high due to the influence of heating gas such as combustion gas. The heat exchanger according to the present invention includes an auxiliary member including a shell tube joint portion joined to a shell tube and an extension portion extending from the shell tube joint portion toward a plurality of fins, and the plurality of fins are disposed so as to be separated from a side wall portion so as to avoid direct contact with the side wall portion of a housing. The extending part of the auxiliary member comprises an entering part entering the space between the fins and the side wall part and a first abutting part arranged on the entering part and abutting against the outer ends of the fins, and the first abutting part is separated from the side wall part. A space portion in which the inflow of the heating gas is s