The present invention aims at providing a composite semipermeable membrane excellent in water permeability and salt-blocking rate, and including an extremely small amount of unreacted polyfunctional amine components in the membrane, and at providing a process for producing the composite semipermeable membrane. A composite semipermeable membrane having a skin layer formed on the surface of a porous support, the skin layer comprising a polyamide resin obtained by interfacial polymerization of a polyfunctional amine component and a polyfunctional acid halide component, wherein the content of an unreacted polyfunctional amine component is 200 mg/m.sup.2 or less after formation of the skin layer and before a membrane washing treatment, and the content of the unreacted polyfunctional amine component after the membrane washing treatment is 20 mg/m.sup.2 or less.