The present invention aims at providing a composite semipermeable membrane
in which water permeability and salt-blocking rate cannot deteriorate by
long-term storage, and at providing a process for producing the same. The
present invention relates to a composite semipermeable membrane having a
skin layer formed on the surface of a porous support, the skin layer
including a polyamide resin obtained by interfacial polymerization of a
polyfunctional amine component and a polyfunctional acid halide
component, wherein the porous support contains at least one kind of
additives selected from the group consisting of antioxidants,
antibacterial agents, antifungal agents, and moisturizers, in an amount
of 95% by weight or more with respect to the whole composite
semipermeable membrane.