A positive photosensitive composition includes: a resin (A) whose dissolution rate in an alkaline developing solution increases by the action of an acid, the resin (A) containing an acid decomposable repeating unit represented by a general formula (I) and an acid nondecomposable repeating unit represented by a general formula (II); and a compound (B) capable of generating an acid upon irradiation with one of active rays and radiations: wherein Xa.sub.1 represents one of a hydrogen atom, an alkyl group, a cyano group, and a halogen atom, A.sub.1 represents one of a single bond and a divalent connecting group, ALG represents an acid leaving hydrocarbon group, Xa.sub.2 represents one of a hydrogen atom, an alkyl group, a cyano group, and a halogen atom, A.sub.2 represents one of a single bond and a divalent connecting group, and ACG represents an acid nonleaving hydrocarbon group.