A method of fabrication of a semiconductor integrated circuit device, calls for disposing, in an ultrapure water preparing system, UF equipment having therein a UF module which has been manufactured by disposing, in a body thereof, a plurality of capillary hollow fiber membranes composed of a polysulfone membrane or polyimide membrane, bonding the plurality of hollow fiber membranes at end portions thereof by hot welding, and by this hot welding, simultaneously adhering the hollow fiber membranes to the body. Upon preparation of ultrapure water to be used for the fabrication of the semiconductor integrated circuit device, it is possible to prevent run-off of ionized amine into the ultrapure water.