Resist composition, method of forming resist pattern and polymeric compound

A resist composition comprising a base component (A) which generates acid upon exposure and exhibits changed solubility in a developing solution under the action of acid,

• the base component (A) comprising a polymeric compound (A1) comprising a structural unit (a0) represented by general formula (a0-1) shown below, a structural unit (a1) containing an acid decomposable group which exhibits increased polarity by the action of acid and a structural unit (a6) which generates acid upon exposure and includes a group represented by general formula (a6-0-1) or (a6-0-2) shown below:
• wherein R1 represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms;
• W represents —COO—, —CONH—or a divalent aromatic hydrocarbon group;
• Y1 and Y2 each independently represents a divalent linking group or a single bond;
• R′1 represents a hydrogen atom;
• R′2 represents a methyl group;
• and R2 is a group represented by general formula (3-1) shown below:
• wherein A′ represents an oxygen atom;
• a represents an integer of 0 to 2;
• and R8 represents an alkyl group,an alkoxy group, a halogenated alkyl group, a hydroxyl group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyano group, wherein R″ represents a hydrogen atom or an alkyl group;
• wherein Q1 and Q2 each independently represents a single bond or a divalent linking group;
• R3, R4 and R5 each independently represents an organic group, provided that R4 and R5 may be mutually bonded to form a ring with the sulfur atom in the formula;
• V−represent a counteranion;
• A−represents an organic group containing an anion;
• and Mm+represents an organic cation having a valency of m, wherein m represents an integer of 1 to 3.