Separation functional layer, separation membrane, and method for manufacturing separation functional layer

A method for manufacturing a separation functional layer including polyimide P, comprising

• forming the separation functional layer by applying a coating liquid containing a material of the separation functional layer onto a base material and drying the coating liquid, wherein
• the polyimide P includes a structural unit A1 derived from a tetracarboxylic dianhydride a1 having a six-membered ring acid anhydride structure, and a structural unit B1 derived from diamine b1, and
• at least one of the structural unit A1 and the structural unit B1 has at least one functional group F selected from the group consisting of a carboxyl group, a hydroxyl group, a thiol group, and metal salts of these groups.