A positive photosensitive composition comprising: (A) a compound capable of generating an acid upon irradiation with actinic rays or radiation; (B1) a resin of which solubility in an alkali developer increases under an action of an acid; and (B2) a resin that has at least one group selected from (a) an alkali-soluble group and (b) a group capable of decomposing under an action of an alkali to produce an alkali-soluble group, and the resin (B2) does not have a group capable of decomposing under an action of an acid; and a pattern forming method using the same.