An exhaust processing device, comprising: a main body tube portion including an opening in an axial end thereof, the main body tube portion housing a main body exhaust path in an inside thereof, the main body exhaust path allowing an exhaust gas to pass therethrough; and a closing tube portion including: a plate portion configured to close the opening of the axial end of the main body tube portion; and a tubular portion radial outwardly protruded from an outer peripheral surface of the main body tube portion, the tubular portion integrated with the plate portion, the tubular portion housing an exhaust path in an inside thereof, the exhaust path communicating with the main body exhaust path, wherein the tubular portion includes: a first split half portion integrally molded with the plate portion; and a second split half portion configured to be joined to the first split half portion, wherein the first split half portion includes a flange portion disposed along an edge thereof and the second split half portion includes a flange portion disposed along an edge thereof, characterized in that the first and second split half portions (24, 27) include convex and concave portions (56, 57) on joint surfaces thereof, the convex portion and the concave portion configured to be engaged for appropriately positioning the first and second split half portions (24, 27), wherein the exhaust processing device further comprises an annular member configured to be fitted onto the tubular portion under a condition that the annular member is abutted to ends of the flange portions (52, 53) for integrating the first split half portion and the second split half portion. a main body tube portion including an opening in an axial end thereof, the main body tube portion housing a main body exhaust path in an inside thereof, the main body exhaust path allowing an exhaust gas to pass therethrough; and a closing tube portion including: a plate portion configured to close the opening of the axial end of the main body tube portion; and a tubular portion radial outwardly protruded from an outer peripheral surface of the main body tube portion, the tubular portion integrated with the plate portion, the tubular portion housing an exhaust path in an inside thereof, the exhaust path communicating with the main body exhaust path, wherein the tubular portion includes: a first split half portion integrally molded with the plate portion; and a second split half portion configured to be joined to the first split half portion, wherein the first split half portion includes a flange portion disposed along an edge thereof and the second split half portion includes a flange portion disposed along an edge thereof, characterized in that the first and second split half portions (24, 27) include convex and concave portions (56, 57) on joint surfaces thereof, the convex portion and the concave portion configured to be engaged for appropriately positioning the first and second split half portions (24, 27), wherein the exhaust processing device further comprises an annular member configured to be fitted onto the tubular portion under a condition that the annular member is abutted to ends of the flange portions (52, 53) for integrating the first split half portion and the second split half portion.