A compound shown by the general formula [1]
(wherein R 1 , R 2 and R 3 are each independently an aromatic hydrocarbon residual group, Y n- is an anion derived from a carboxylic acid having 3 or more carbon atoms with substituted fluorine atoms, and n is 1 or 2, provided that R 1 , R 2 and R 3 each is not a phenyl group having substituents at an ortho and/or a meta position), and a composition consisting of the compound and a diazodisulfone compound are disclosed. Use of the compound or the compound as an acid generator for resists produces the effects of improving the profiles of ultra-fine patterns or diminishing sidewall irregularities in ultra-fine patterns. The compound is also useful as a cationic photopolymerization initiator.