An alignment treating agent for a liquid crystal cell, which comprises an organic solvent-soluble polyimide resin having a reduced viscosity of from 0.05 to 3.0 dl/g (concentration: 0.5 g/dl in N-methylpyrrolidone at 30??? C.) and having the formula (1): ##STR7## wherein R1 is a tetravalent organic group constituting a tetracarboxylic acid and its derivative, R2 is a bivalent organic group constit