A positive resist composition that includes a resin component (A) that exhibits increased alkali solubility under action of acid, and an acid generator component (B) that generates acid on exposure, wherein the component (A) is a copolymer (A1) that includes a structural unit (a1) derived from an acrylate that contains an acid dissociable, dissolution inhibiting group, a structural unit (a2) derived from an α-lower alkyl acrylate that contains a lactone ring, and a structural unit (a3) derived from an (α-lower alkyl)acrylate that contains a polar group-containing polycyclic group.