To provide a method for profitably and industrially producing highly pure 2,6-dimethylnaphthalene from a dimethylnaphthalene mixture.

This method for producing the highly pure 2,6-dimethylnaphthalene is characterized by comprising (1) an isomerization process for isomerizing a dimethylnaphthalene mixture in the presence of a catalyst, (2) a crystallization process for separating the 2,6-dimethylnaphthalene from the isomerization reaction product by a crystallization method in the presence of a solvent, and (3) a distillation process for distilling the mother liquid of the crystallization process to remove components having higher boiling points and components having lower boiling points than that of the dimethylnaphthalene to obtain the dimethylnaphthalene fraction, wherein the dimethylnaphthalene fraction obtained by the distillation process is returned to the isomerization process.