Abstract: A molding resin composition for preparing molded pieces which are suited to laser masking. The composition comprises a thermosetting resin, a curing agent, an inorganic white filler and 0.1 to 3% by weight of a coloring agent represented by the formula (I) ##STR1## wherein R.sub.1 and R.sub.2 are each hydrogen, halogen, C.sub.1 -C.sub.8 alkyl, substituted or unsubstituted sulfonamido or SO.sub.2 CH.sub.3 ; R.sub.3 and R.sub.4 are each hydrogen, C.sub.1 -C.sub.8 alkyl, or substituted or unsubstituted carbonamido; M is Cr, Fe or Co; and A is H, NH.sub.4, ammonium ion of a primary, secondary or tertiary amine or quaternary ammonium ion.