This invention relates to an improved process for producing 2,6-dichloro-3,5-di(secondary or tertiary alkyl)toluene represented by the following formula (I). The process comprises chlorinating 3,5-di(secondary and tertiary alkyl)toluene represented by the following formula (II) by reacting with a chlorinating agent in the presence of a Lewis acid together with an aromatic sulfur compound represented by the formula (III) as a promoter: wherein R1 and R2 are independently a secondary alkyl or tertiary alkyl group, Ar1 and Ar2 are independently an unsubstituted or substituted aromatic ring, and n is 1 or 2.