A solvent-free polyimide silicone resin composition comprising (a) a polyimide silicone resin having repeating units represented by the following formula (1-1) and repeating units represented by the following formula (1-2), a film of said resin with a thickness of 100 .mu.m prepared on a quartz glass substrate having a light transmittance of 80% or higher at wavelengths of from 350 nm to 450 nm, (b) a reactive diluent, and (c) a photopolymerization initiator ##STR00001## wherein X is a tetravalent organic group, Y is a divalent organic group, and Z is a divalent organic group represented by the following formula (2), ##STR00002## wherein R.sup.1 may be different from each other and is a monovalent hydrocarbon group having 1 to 8 carbon atoms, which group may be substituted, R.sup.2 is a monovalent hydrocarbon group having a photopolymerizable group, a and b are each an integer of from 1 to 100 with a+b.ltoreq.100.