Abstract: A hollow fiber membrane module includes: a tubular container accommodating a hollow fiber membrane bundle; headers, and potted parts. The header includes a header protrusion that protrudes in an annular shape toward the tubular container. The tubular container includes double annular protrusions, which are an inner protrusion and an outer protrusion protruding toward the header. The header and the tubular container are welded together by ultrasonic welding, with the header protrusion being inserted between the inner protrusion and the outer protrusion of the tubular container. The header protrusion and the inner protrusion of the tubular container are welded together at least in one or more regions, and the header protrusion and the outer protrusion of the tubular container are welded together at least in one or more regions.

Abstract: The hollow fiber membrane module according to the present application is provided with a cylindrical container open at one end and the other end, a bundle of hollow fiber membranes packed in the cylindrical container, potting parts embedding and fixing the bundle of hollow fiber membranes at both ends of the cylindrical container, and headers provided at both ends of the cylindrical container and having nozzles that constitute an inlet and outlet for a fluid. In this hollow fiber membrane module, the headers and the cylindrical container are welded in at least two areas including a primary weld and a secondary weld, and the secondary weld is located in a position where welding is initiated after or simultaneously with the beginning of welding of the primary weld.

Abstract: A hollow fiber membrane blood purifying device including a cylindrical container, a hollow fiber membrane bundle, a potting resin fixing portion embedding and fixing the hollow fiber membrane bundle at each end of the cylindrical container, headers having nozzles, and ports further has the structure in which each header and the cylindrical container are welded in at least two regions over the circumference. The inside face of the header is in contact with a potting resin fixing portion cut face that is formed by cutting an outer side portion of the potting resin fixing portion in the length direction of the cylindrical container than the end face of each end of the cylindrical container, and the potting resin fixing portion cut face is in a compressively deformed state.