Provided is a reverse osmosis membrane in which a highly chemical-resistant (alkali-resistant and chlorine-resistant) material is used and yet which shows desalting ability and water permeability, said properties being required in treating waste water, both at a high level. A reverse osmosis membrane for treating waste water which comprises a sulfonated polyarylene ether sulfone polymer containing a component represented by general formula [I], characterized in that, in a proton nuclear magnetic resonance spectrum obtained by measuring water molecules in said reverse osmosis membrane that is in a water-retaining state, the relationship between chemical shift (A) (ppm) of a spectrum peak top arising from bound water and chemical shift (B) (ppm) of a spectrum peak top arising from bulk water satisfies the requirement B-0.36<=A