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.