COMPOSITE SEMIPERMEABLE MEMBRANE AND PRODUCTION METHOD FOR COMPOSITE SEMIPERMEABLE MEMBRANE

The present invention relates to a composite semipermeable membrane comprising a substrate, a support layer, and a separation function layer, wherein: the support layer includes particles and a thermoplastic resin having a porous structure; the particles are present in the thermoplastic resin and contain at least one material selected from the group consisting of a diene polymer, an acrylic polymer, and an ethylenic polymer; and in a cross section of the support layer, taken in the laser thickness direction, 6 or more of the particles are present in an area which is 3 μm from the surface of the support layer in the layer thickness direction and 3 μm in the direction along which such surface extends.