Disclosed is a positive resist composition which can provide a positive resist composition and a resist pattern forming method, capable of forming a high resolution pattern with reduce LER, the positive resist composition comprising a resin component (A) which has acid dissociable, dissolution inhibiting groups and exhibits increased alkali solubility under the action of an acid, and an acid generator component (B) which generates an acid under exposure, wherein the resin component (A) contains a polymer compound (A1) having a structural unit (a1) derived from hydroxystyrene and a structural unit (a2) derived from an acrylate ester having acid dissociable, dissolution inhibiting groups, a fluorine atom or a fluorinated lower alkyl group being bonded at the α-position.