To provide a resist composition for developing, by an alkaline water solution, a positive type pattern, high in sensitivity, high in resolution, and good in stability, and a pattern forming method using it.

In a chemically amplifying resist composition including, at least, an alkali-soluble resin, a medium for changing solubility of an alkaline solution by a reation using an acid as a catalyst, and an acid precursor for producing an acid by radiation exposure, an organic salt having an anion site expressed by a general formula 1 being an alkyl sulfonic acid or an aryl sulfonic acid, is added to the resist composition. In the formula, R1, R2, R3, and R4 are alkyl radicals having 1 to 6 carbon atoms or substituted alkyl radicals, Y- stands for an alkyl sulfonic acid or an aryl sulfonic acid.