Abstract: Insulating varnishes capable of forming a film possessing excellent electrical and mechanical properties can be obtained by reacting a reaction product of (1) a reactant of a dicarboxylic acid or a tricarboxylic acid or a derivative thereof comprising an aromatic dicarboxylic acid or a derivative thereof in an amount of at least 95 equivalent % [the term "equivalent" as used herein means (number of moles) x (number of reactive functional groups in one molecule)] of the total of the (1), (2) a primary diol and (3) an aliphatic polyhydric alcohol having at least 3 hydroxyl groups with (4) an aromatic teracarboxylic acid or derivative thereof, and subsequently dispersing the reaction product into an aqueous solution containing ammonia or an organic amine.