Resist composition and method of forming resist pattern

A resist composition which generates an acid upon exposure and whose solubility in a developing solution is changed due to an action of the acid, the resist composition comprising:

• a resin component (A1) whose solubility in a developing solution is changed due to the action of the acid,
• wherein the resin component (A1) has a constitutional unit (a0-1) derived from a compound represented by Formula (a0-1) and a constitutional unit (a0-2) derived from a compound represented by Formula (a0-2):
• wherein W represents a polymerizable group-containing group, and Ra01 represents an acid dissociable group represented by Formula (a01-r-1) or (a01-r-2):
• wherein Ra011 to Ra013 each independently represents a linear or branched aliphatic hydrocarbon group, Ra014 represents a linear or branched aliphatic hydrocarbon group, Ra015 represents a group that forms a monocyclic aliphatic cyclic group together with a carbon atom to which Ra014 is bonded, and the symbol “*” represents a bonding site;
• wherein W represents a polymerizable group-containing group, and Ra02 represents an acid dissociable group represented by Formula (a02-r-1):
• wherein Ra021 and Ra022 each independently represents a linear or branched aliphatic hydrocarbon group, Ra023 represents an aromatic hydrocarbon group which may have a substituent, and the symbol “*” represents a bonding site.