There is provided a positive resist composition including a resin component (A) which displays increased solubility in an alkali developing solution under action of acid, and an acid generator component (B) which generates an acid upon exposure, wherein the resin component (A) includes a polymer compound (A1) containing a structural unit (a0) represented by a general formula (a0-1) shown below, and a structural unit (a1) derived from an acrylate ester which has an acid dissociable, dissolution inhibiting group: (in the formula (a0-1), R represents a hydrogen atom, a lower alkyl group, or a halogenated lower alkyl group; two of R′ each independently represents a hydrogen atom, a lower alkyl group, or an alkoxy group of 1 to 5 carbon atoms; X represents an alkylene group of 1 to 5 carbon atoms, an oxygen atom, or a sulfur atom.).