A trifluoromethylthiophenium derivative salt useful as synthetic intermediates for pharmaceuticals and agrochemicals, a method for producing the same, and a method for producing trifluoromethyl-containing compounds using the same are provided. An S-(trifluoromethyl)-benzo[b]thiophenium derivative salt is represented by the following general formula (1): wherein R1, R2, R3, and R4 are each independently a hydrogen atom, a methyl group, an ethyl group, a linear, branched, or cyclic alkyl group having 3 to 10 carbon atoms, a methoxy group, an ethoxy group, a linear, branched, or cyclic alkyloxy group having 3 to 10 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, a nitro group, or a cyano group, R5 is a methyl group, an ethyl group, a linear, branched, or cyclic alkyl group having 3 to 10 carbon atoms, a phenyl group, or a substituted phenyl group, and X− represents an anion. Various trifluoromethyl-containing compounds are produced using a method for producing the S-(trifluoromethyl)-benzo[b]thiophenium derivative salt, and using the S-(trifluoromethyl)-benzo[b]thiophenium derivative salt as a trifluoromethylating agent.