Microporous supported on the film a composite semipermeable membrane obtained by forming a polyamide separating functional layer by polycondensation reaction between a polyfunctional aromatic amine and a polyfunctional acid halide, a polyamide separation functional layer is carboxy, amino group, a phenolic hydroxyl group, having an azo group, molar equivalents of molar equivalents + phenolic hydroxyl molar equivalents / (azo group of the amino group ratio X _{a (amino} group in the raw water contacting surfaces of the polyamide separating functional layer (a surface) + moles of amino group equivalent)) is in the range of 0.5 or less and an amino group ratio X _{B (the} amino group in the permeate side of the surface opposite of the polyamide separating functional layer (B surface) of the surface a molar equivalent / composite semipermeable membrane (molar equivalent of molar equivalents + amino group of molar equivalents + phenolic hydroxyl azo groups)) is in the range of 0.5 to 1.. The present invention achieves both high solute removal properties and high water permeate flow, and to provide a composite semipermeable membrane and its manufacturing method having high organic solvent resistance.