Hollow fiber membrane module and dehumidifier/humidifier

A hollow fiber membrane module, comprising:

• a cylindrical outer case;
• an inner case that is arranged inside the outer case;
• a plurality of hollow fiber membranes that are provided in an annular gap between the outer case and the inner case;
• and
• a pair of sealing fixing portions that seal the annular gap on one end side and an other end side of the outer case and the inner case respectively in a state in which hollow interiors of the hollow fiber membranes are open, and fix the plurality of hollow fiber membranes to the outer case and the inner case,
• wherein an outer peripheral surface of the inner case includes a one-end-side outer peripheral surface, the width of which in a direction perpendicular to a direction from the one end side to the other end side is constant from the one end side toward the other end side, and
• an other-end-side outer peripheral surface which is provided closer to the other end side than the one-end-side outer peripheral surface and the width of which gradually widens from the one end side toward the other end side,
• wherein, in the inner case, a hollow portion that opens to the other end side is provided on an inside of the other-end-side outer peripheral surface, and a plurality of windows that allow communication between the hollow portion and the annular gap are provided, and
• wherein, in the outer case, a communication hole that communicates between the annular gap and the outside of the outer case is provided at a position that is closer to the one end side.