A compound represented by the general formula [1] [1] (wherein R , R , and R each independently represents a residue of an aromatic hydrocarbon; Y represents an anion derived from a fluorinated carboxylic acid having three or more carbon atoms; and n is 1 or 2, provided that R , R , and R each is not a phenyl group having a substituent in an ortho and/or a meta position); and a composition comprising the compound and a diazodisulfone compound. Use of the compound or the composition as an acid generator for resists produces the effect of improving the profiles of ultrafine patterns or diminishing side wall irregularities in ultrafine patterns. The compound is also useful as a cationic photopolymerization initiator.