Abstract: An aqueous alkali developable photoresist composition consists of (a) a carboxyl group-containing polymeric binder, (b) 1-15% by weight of a photoinitiator based on the binder, (c) 20-100% by weight based on the binder, of a photo reactive monomer or oligomer containing at least two ethylenically unsaturated double bonds, and (d) 0.05-5% by weight based on the binder of a weak alkali soluble or dispersible thiol compound represented by(X).sub.a R--SH).sub.bwhere a, b are integers equal to or greater than 1, R is an organic moiety of molecular weight less than 500, and X is a carboxyl group-containing moiety or hydrophilic organic polymeric segment with less than 100 repeating unit.