A method for preparing a sulfone represented by the following formula: ##STR1## wherein R and R' each represent a lower alkyl group, an aryl group or an aryl group whose nucleus has at least one substituent selected from the group consisting of a halogen atom, nitro group, a lower alkyl group, phenyl group and a phenyl group substituted with a halogen atom, comprises the step of condensing a sulfonic acid ester of 4-hydroxybiphenyl represented by the following formula: ##STR2## with a sulfonyl chloride of R'SO.sub.2 Cl at a temperature of 0.degree. to 200.degree. C. in the presence of a Lewis acid or a superstrong acid.