The present invention provides a separation membrane suitable for separating water from a liquid mixture containing an alcohol and water. A separation membrane 10 according to the present invention contains polyimide including a structural unit represented by formula (1). A is a linking group having a solubility parameter, in accordance with a Fedors method, of more than 5.0. B is a linking group having a solubility parameter of more than 8.56. R 1 to R 6 each are independently a hydrogen atom, a halogen atom, a hydroxyl group, a sulfonic group, an alkoxy group having 1 to 30 carbon atoms, or a hydrocarbon group having 1 to 30 carbon atoms. Ar 1 and Ar 2 each are a divalent aromatic group.