A resin intake manifold is provided with two separated bodies manufactured by connecting protrusions of weld portions of the separated bodies to each other in accordance with a vibration welding, and a cover wall in which one of the weld portions is arranged in an inner side or an outer side of the protrusion with leaving space with the protrusion. The protrusions of the weld portions are respectively provided with parallel protrusion portions extending in parallel to a vibrating direction of the vibration welding, and a cover wall arranged at a position in an orthogonal direction to the vibrating direction in the parallel protrusion portions is provided with an extension portion extending to the separated body in the other side welded to the separated body provided with the cover wall, in such a manner as to prevent a burr generated at a time of welding the parallel protrusion portion from getting over the cover wall arranged at the position in the orthogonal to the vibrating direction in the parallel protrusion portion. A recess groove receiving the extension portion is arranged in a side of the other side separated body.