A water-soluble resin composition for forming fine patterns comprising water-soluble polymer represented by Chemical Formula 1 as below and the first water-soluble solvent, is coated and heated on a photoresist layer having at least one contact hole to reduce a size of the at least one contact hole. (In Chemical Formula 1, each of R1, R2, R3 and R5 independently represents an alkyl group of C1-30 or an cyclo alkyl group of C3-30 which respectively have one selected from the group consisting of hydrogen, an ether group, an ester group, a carbonyl group, an acetal, an epoxy group, a nitril group, an amine group, and an aldehyde group; each of R4, R6, R7 and R8 independently represents hydrogen or a methyl group; n represents an integer of 0 to 5; a represents a real number of 0.05 to 0.5; each of b, c and d respectively represents a real number of 0 to 0.7; and a+b+c+d=1).