Body fluid filtration device of hollow fiber membrane type, and method for filtrating protein solution

Provided is a body fluid filtration device of a hollow fiber membrane type, whereby it becomes possible to increase the amount of a protein solution which can treated until the pressure in a filtration device increases and it also becomes possible to filtrate out unnecessary biological components from a protein solution containing the unnecessary biological components. A body fluid filtration device of a hollow fiber membrane type (20) is equipped with a filtrating device of a hollow fiber membrane type (1) having an inlet port (11) and a filtrate outlet port (9). The filtrating device of a hollow fiber membrane type (1) is placed transversely in such a manner that the inlet port (11) is located on the upper side, and is so configured that a protein solution containing unnecessary biological components which flows into through the inlet port (11) can pass through a hollow fiber membrane (4) in a downward direction and a protein solution filtrate which flows out from the hollow fiber membrane (4) can be discha