Disclosed is a novel undercoating solution for the formation of an antireflection undercoating layer to intervene between the surface of a substrate and a photoresist layer to be patterned in the manufacturing process of semiconductor devices with an object to prevent adverse influences of the light reflecting at the substrate surface on the cross sectional profile of the patterned resist layer. The undercoating composition is a uniform solution which comprises: (A) a nitrogen-containing organic compound having, in a molecule, at least two amino groups substituted by at least one substituent group selected from the group consisting of hydroxyalkyl groups and alkoxyalkyl groups such as an N,N-substituted benzoguanamine compound; (B) an organic acid or an inorganic acid of which the acid residue contains at least one atom of sulfur such as methanesulfonic acid and dodecylbenzene sulfonic acid; and (C) an organic solvent such as propyleneglycol monomethyl ether. The undercoating solution further optionally contains a light-absorbing compound such as bis(4-hydroxyphenyl) sulfone and 9-hydroxymethyl anthracene.