The present invention provides a novel diamine which is especially useful as a material for a resin for a liquid crystal alignment film, a polyimide precursor and a polyimide synthesized by using the diamine, and a treating agent for liquid crystal alignment containing such a polymer, which gives a liquid crystal alignment film having a high pretilt angle of liquid crystal, excellent thermal stability of the pretilt angle and small dependence of the pretilt angle on rubbing pressure.A diaminobenzene derivative represented by the formula (1): ##STR00001## wherein X.sub.1 and X.sub.2 are cyclic groups, and X.sub.3 is selected from an alkyl group, an alkoxy group, a fluoroalkyl group, a fluoroalkoxy group, a fluorine atom, a chlorine atom, a bromine atom and a cyano group; a polyimide precursor and a polyimide synthesized by using the diaminobenzene derivative as a part of the material; and a treating agent for liquid crystal alignment containing at least one of the polymers.