A positive resist composition, which comprises: (A) a resin of which solubility in an alkali developer increases under an action of an acid; (B) a compound capable of generating an acid upon irradiation with actinic rays or radiation; (C) a resin having at least one of a fluorine atom and a silicon atom; and (D) a solvent, wherein the resin (C) contains at least one of: (C1) a resin having at least one of a fluorine atom and a silicon atom and having an alicyclic structure; and (C2) a resin containing a repeating unit having at least one of a fluorine atom and a silicon atom in a side chain and a repeating unit having an unsubstituted alkyl group in a side chain; and a pattern forming method.