There is provided a positive type resist composition formed by dissolving (A) a resin component with a unit derived from a (meth)acrylate ester in the principal chain, for which the solubility in alkali increases under the action of acid, and (B) an acid generator component which generates acid on exposure, in an organic solvent component (C), wherein the resin component (A) is a copolymer comprising (a1) a unit derived from a (meth)acrylate ester comprising an acid dissociable, dissolution inhibiting group containing a polycyclic group, (a2) a unit derived from a (meth)acrylate ester comprising a lactone containing monocyclic group or polycyclic group, (a3) a unit derived from a (meth)acrylate ester comprising a hydroxyl group containing polycyclic group, and (a4) a unit derived from a (meth)acrylate ester comprising a polycyclic group which is different from the unit (a1), the unit (a2) and the unit (a3). This composition provides a chemically amplified positive type resist composition which displays excellent resolution, enables the depth of focus range of an isolated resist pattern to be improved, and enables the proximity effect to be suppressed.