SEPARATION MEMBRANE AND METHOD FOR PRODUCING SAME

For the purpose of providing a separation membrane which is excellent in terms of low fouling properties, separation performance and water permeability, while having high chemical resistance, a separation membrane according to the present invention comprises a porous resin layer that contains a polymer which is mainly composed of a polyvinylidene fluoride resin, and this separation membrane is configured such that: with respect to the porous resin layer, the number A of pores having a surface pore diameter of not less than 0.01 μm but less than 0.05 μm and the number B of pores having a surface pore diameter of 0.05 μm or more satisfy the relational expression 2.0 ≤ A/B ≤ 15.0; and the void fraction of macrovoids having a breadth of 10 μm or more in a region from the surface to the depth of 15 μm of the porous resin layer is from 15% to 80%.