PURPOSE: To obtain the subject varnish having excellent viscosity stability and capable of increasing the concentrations of resins in spite of using water as a solvent by containing a polyimide precursor obtained from a polyamic acid, each a specific amine compound and an organic solvent.

CONSTITUTION: (A) A polyamic acid of the formula (A and B are each an aromatic group or a fatty group; (n) is 17-2920) is reacted with (B) an amine compound selected from 2-dimethylaminoethanol, 2-diethylaminoethanol, 2- methylaminodiethanol, dimethyl-3-butanol, diethylamino-acetone, N- ethylaminodiethanol, N-methylaminoethanol, 2,2-aminodiethanol, 3-diethylamino-1- propanol and amino-cyclohexane and (C) an organic solvent selected from N,N- dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide and N,N-DMF and the resultant polyimide precursor as a reaction product is added with water to obtain the objective varnish.