Abstract: A hollow fiber membrane module includes a pressure vessel, a plurality of hollow fiber membrane elements arranged in series inside the pressure vessel, and a connector that connects the hollow fiber membrane elements to each other. Each of the hollow fiber membrane elements includes a plurality of hollow fiber membranes, and a double-core tube extending in a longitudinal direction of the plurality of hollow fiber membrane elements. The connector includes a first channel and a second channel that do not communicate with each other. Between the hollow fiber membrane elements, the outer channels of the hollow fiber membrane elements are connected to each other through the first channel, the inner channels of the hollow fiber membrane elements are connected to each other through the second channel, and hollow portions of the hollow fiber membranes communicate with the inner channels through the second channel.