To provide a positive radiation-sensitive resin composition superior in sensitivity and resolution and good in environmental resistance.

The positive radiation-sensitive resin composition comprises (A) an alkali-soluble resin having phenolic hydroxyl groups or at least one part of the above hydroxyl groups being protected with an acid-decomposable protective group, (B) a compound having a partial structure decomposable by an action of an acid and capable of producing a group for giving alkali- solubility upon decomposition and (C) a compound to be decomposed by activated rays or radiation resulting in generating an acid and the compound (B) can be embodied by a compound having, as the partial structure to be decomposed by an acid and to give the alkali solubility, a partial structure of an optionally substituted ≥7C alkyl carbonate group.