Positive resist composition and pattern-forming method using the same

A positive resist composition comprising:

• (A) a resin capable of increasing a solubility thereof in an alkali developer by an action of an acid, the resin containing a repeating unit having a group having a lactone structure;
• (B) a compound capable of generating a sulfonic acid represented by the following formula (I) upon irradiation with one of an actinic ray and a radiation;
• and
• (C1) at least one of an amine compound having at least an aliphatic hydroxyl group in a molecule and an amine compound having at least an ether bond in a molecule:
• A1A2-SO3H)n (I)
• wherein A1 represents an n-valent linking group, A2 represents a divalent aliphatic group, and A2's each may be the same or different, provided that at least one group represented by A1 or A2 contains a fluorine atom, and n represents an integer of from 2 to 4.