PURPOSE: To obtain a charge type ultrafiltration film by introducing sulfonic acid groups into the outer and porous surfaces of the ultrafiltration film made of aromatic polysulfone into the form of a hollow fiber.

CONSTITUTION: The outer and porous surfaces of ultrafiltration film made of aromatic polysulfone into the form of a hollow fiber have sulfonic acid groups and are cross-linked. A charge type ultrafiltration film is formed by chloroalkylating the outer and porous surfaces of the aforesaid ultrafiltration film with a chloroalkyl compound and introducing sulfonic acid groups thereinto using hydrogensulfite. The hydrocarbon solvent which has the characteristics of being poor in the dissolution of the aforesaid aromatic polysulfone and good in that of the chloroalkylating agent is used as a solvent in the manufacturing of the above ultrafiltration film.