Abstract: A composite semipermeable membrane, including: a microporous support layer; and a separation functional layer provided on the microporous support layer, in which the separation functional layer includes a crosslinked wholly aromatic polyamide which is a polycondensation product of a polyfunctional aromatic amine and a polyfunctional aromatic acid chloride and contains amino groups and carboxyl groups, and in positive secondary ions measured on a surface of the separation functional layer by time-of-flight secondary ion mass spectrometry, when (count number of m/z=104.03)/(count number of m/z=108.06) is denoted by a, and a molar ratio (carboxyl group/amino group) of the carboxyl group to the amino group, which is obtained by analyzing the entire separation functional layer by 13C solid state NMR, is denoted by b, the following formulae (1) and (2) are satisfied: a?5.0 (1); and a/b?4.3 (2).

Abstract: The present invention relates to a composite semipermeable membrane including: a support membrane including a base and a porous support layer; and a separation functional layer disposed on the porous support layer and including a crosslinked aromatic polyamide, in which the separation functional layer contains sulfo groups in an amount of 7.0×10?5 to 5.0×10?2 g/m2 and includes a structure represented by the formula 1.