A hollow fiber membrane module for water exchanging comprising: a housing including a first fluid inlet through which a first fluid of low-humidity is supplied, a second fluid inlet through which a second fluid of high-humidity is supplied, a first fluid outlet through which the first fluid is discharged, and a second fluid outlet through which the second fluid is discharged;; diaphragms in the housing, the diaphragms having fluid flow holes a plurality of hollow fiber membrane bundles divided from each other by the diaphragms respectively surrounding the plurality of hollow fiber membrane bundles, each of the hollow fiber membrane bundles including a plurality of hollow fiber membranes; and potting parts configured to fix both ends of the hollow fiber membranes to the housing and contacting both ends of the housing, wherein the diaphragms and hollow fiber membrane bundles are disposed within the housing in such a way that the first fluid flows inside the hollow fiber membranes and the second fluid flows outside the hollow fiber membranes, and the first fluid and the second fluid exchange moisture with each other through the hollow fiber membranes, wherein each of the hollow fiber membrane bundles further includes a porous tube disposed between the plurality of hollow fiber membranes, the porous tube being vacant and having both ends potted in the potting parts but closed so as to prevent the first fluid supplied into the housing via the first fluid inlet from flowing into an inside of the porous tube, wherein length direction of the respective porous tube coincides with the length direction of the hollow fiber membrane bundles, wherein the respective porous tube has a plurality of pores formed on the side surfaces thereof so that the second fluid is allowed to flow into and along the inside of the porous tube, the pores having a diameter of 1 to 10 mm, and wherein the housing includes: a housing body having both ends opened and including the second fluid inlet and the second fluid outlet respectively formed on circumferential parts surrounding the potting parts; and housing caps combined with the respective ends of the housing body and including the first fluid inlet and the first fluid outlet. a housing including a first fluid inlet through which a first fluid of low-humidity is supplied, a second fluid inlet through which a second fluid of high-humidity is supplied, a first fluid outlet through which the first fluid is discharged, and a second fluid outlet through which the second fluid is discharged;; diaphragms in the housing, the diaphragms having fluid flow holes a plurality of hollow fiber membrane bundles divided from each other by the diaphragms respectively surrounding the plurality of hollow fiber membrane bundles, each of the hollow fiber membrane bundles including a plurality of hollow fiber membranes; and potting parts configured to fix both ends of the hollow fiber membranes to the housing and contacting both ends of the housing, wherein the diaphragms and hollow fiber membrane bundles are disposed within the housing in such a way that the first fluid flows inside the hollow fiber membranes and the second fluid flows outside the hollow fiber membranes, and the first fluid and the second fluid exchange moisture with each other through the hollow fiber membranes, wherein each of the hollow fiber membrane bundles further includes a porous tube disposed between the plurality of hollow fiber membranes, the porous tube being vacant and having both ends potted in the potting parts but closed so as to prevent the first fluid supplied into the housing via the first fluid inlet from flowing into an inside of the porous tube, wherein length direction of the respective porous tube coincides with the length direction of the hollow fiber membrane bundles, wherein the respective porous tube has a plurality of pores formed on the side surfaces thereof so that the second fluid is allowed to flow into and along the inside of the porous tube, the pores having a diameter of 1 to 10 mm, and wherein the housing includes: a housing body having both ends opened and including the second fluid inlet and the second fluid outlet respectively formed on circumferential parts surrounding the potting parts; and housing caps combined with the respective ends of the housing body and including the first fluid inlet and the first fluid outlet. a housing body having both ends opened and including the second fluid inlet and the second fluid outlet respectively formed on circumferential parts surrounding the potting parts; and housing caps combined with the respective ends of the housing body and including the first fluid inlet and the first fluid outlet.