Hollow fiber membrane module

A hollow fiber membrane module comprising:

• an inner case that is a member with a tubular shape;
• an outer case that is a member with a tubular shape covering the inner case from an outer periphery side with a space left therebetween;
• at least one bypass pipe that connects to the inner case in the space between the inner case and the outer case;
• and
• a plurality of hollow fiber membranes that are provided in the space between the inner case and the outer case, wherein
• the inner case includes an introduction portion that is a part establishing communication between inside of the inner case and outside of the inner case on a side of one end in an extending direction of the inner case and the outer case,
• the outer case includes a discharge portion that is a part establishing communication between inside of the outer case and outside of the outer case on a side of another end in the extending direction,
• the inner case includes at least one bypass port penetrating through the inner case between the inside of the inner case and the outside of the inner case on a side closer to the another end in the extending direction than the introduction portion,
• the bypass pipe communicates with the bypass port and is capable of forming a fluid path that connects the bypass port and the discharge portion, and
• wherein the bypass pipe connects to the outer case in the space between the inner case and the outer case, communicates with the discharge portion, and connects the bypass port and the discharge portion.