Abstract: A photosensitive hardenable composition comprising as major components a thermoplastic high molecular binder obtained from specific addition polymerizable monomers, an acrylate (or methacryliate) derivative or mixture thereof and a photopolymerization initiator, which possesses improved properties in softness, stripping properties, stripping time, etc. of hardened layers formed.

Abstract: The initiator composition is effectively used for a photopolymerizable resin composition which comprises a photopolymerizable compound having a double bond for polymerization and a polymer binder and comprises (A) thioxanthone or a substituted thioxanthone and (B) an oxime ester of the formula: ##STR1## wherein R.sub.1 and R.sub.2 may be the same or different and represent each an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted phenyl, naphthyl, anthryl, pyridyl or quinolyl group or R.sub.1 and R.sub.2 may be bonded together to form a ring, and R.sub.3 represents an alkyl group having 1 to 5 carbon atoms or a substituted or unsubstituted aryl group.