Positive image forming radiation sensitive compositions containing diazide compound and organic cyclic anhydride

A radiation-sensitive composition capable of producing a positive image upon exposure to actinic radiation and subsequent treatment with a basic solution which consists essentially of, by weight based on weight of the total composition, (a) 10 to 50 weight percent of an o-naphthoquinone diazide compound, (b) 45 to 79 weight percent of an alkali soluble film-forming phenolic resin and (c) 1 to 15 weight percent of an organic acid cyclic anhydride represented by the following formulae (II) or (III) ##STR3## wherein R.sub.1 and R.sub.2 each represents a hydrogen atom, a halogen atom, an unsubstituted or substituted alkyl group, or an unsubstituted or substituted aryl group, and R.sub.1 and R.sub.2 may combine together to form a cyclic ring.