A gas separation membrane has a gas separation layer containing a poly(benzoxazole-imide) compound in which the poly(benzoxazole-imide) compound having structural units represented by General formulae (I) and (II), or structural units represented by General formulae (I), (II) and (III) satisfies a specific molar quantity condition. In the formulae, X and Y each represent a single bond or a specific divalent linking group; L represents a specific divalent linking group including a phenylene group; and R represents a specific group. A gas separation module and a gas separation method use the gas separation membrane. A gas separation apparatus includes the gas separation module.