PURPOSE: To obtain the composition suitable for a coating without using any organic solvent, capable of forming a colorless transparent coating film having good water resistance, chemical resistance and adhesion, by combining a specific molecular weight formaldehyde condensation product as a part of its components.

CONSTITUTION: A water-based resin composition contains as a part of its components, a condensation product of formaldehyde with 1 mole of a phenolic compound and 0.5-0.05 mole of an aromatic aminosulfonic acid, having an average molecular weight of 2000-500000. Also the composition contains the condensation product with one mole of a bisphenol and 0.75-0.05 mole of the aromatic amino acid, having an average molecular weight of 2000-50000. The bisphenol is expressed by the formula (wherein, X is CH2, SO2, O, etc.). The formaldehyde condensation product of 100wt.pt. is used by combining with 5-200wt.pt. of a component containing a functional group capable of reacting with amino group, methylol group, etc., a water-based melamine resin, a water-based epoxide resin, a water-based urethane resin or a water-based blocked isocyanate. This composition is used for an ink, a coating material, etc.