A method for producing an oxidized cyclic phenol sulfide which comprises the step of oxidizing a cyclic phenol sulfide of the following formula (1) as a raw material: wherein R represents a straight or branched alkyl group having 1 to 6 carbon atoms, and m is an integer from 4 to 8,in a solvent(s) other than a halogenated hydrocarbon in an amount of 2 or more and less than 10 parts by weight per 1 part by weight of the cyclic phenol sulfide, with an oxidizing agent(s) to obtain an oxidized cyclic phenol sulfide of the following formula (2): wherein R represents a straight or branched alkyl group having 1 to 6 carbon atoms, m is an integer from 4 to 8, and n is 1 or 2.