The invention aims to provide a resin composition having favorable stain resistance and storage stability even in the form of a one-pack coating material. Provided is a resin composition for a coating material, including: (I) a synthetic resin emulsion; (II) a silicon compound represented by the formula (1): (R1O)4-aSiR2a  (1) wherein R1s are the same or different and each represent an alkyl group having 1-10 carbon atoms, an aryl group having 6-10 carbon atoms, or an aralkyl group having 7-10 carbon atoms; R2s are the same or different and each represent an alkyl group having 1-10 carbon atoms, an aryl group having 6-10 carbon atoms, or an aralkyl group having 7-10 carbon atoms; and a represents an integer from 0 to 2; and/or a partial hydrolysis condensation product thereof and/or a modified product thereof; and (III) a photosensitizer.