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 discharged through the f