PURPOSE: To provide a filter in which an organic hollow fiber membrane such as a superfiltration MF membrane and an ultrafiltration membrane and an inorganic multilumen type membrane are used in a casing housing method.

CONSTITUTION: In a casing housing method in which a hollow yarn permeation membrane such an organic super filtration membrane and a ultrafiltration membrane and inorganic multilumen type membrane are put in a case and used, in front of the section of a membrane module, that is, between a membrane case 2 and inflow piping 3, a propeller-shaped rotor 6 is fitted, or in the central part between the membrane case 2 and the inflow piping 3, a disc-shaped baffle plate is fitted. In the execution of this method, as the installation place of the rotor 6 and the inflow piping 3, the inside of a reducing size fitting 5 is selected when the membrane case 2 and the inflow piping 3 are connected by the reducing size fitting 5, and the region in front of the membrane module is selected when the membrane case 2 of the membrane module and the inflow piping 3 are integrated.