PURPOSE:To industrially, advantageously and selectively remove impurities, by using a gaseous fraction produced in dehydrogenation reaction as a hydrogen source in purifying styrenes containing highly unsaturated impurities through hydrogenation treatment in the presence of a hydrogenation catalyst. CONSTITUTION:Styrenes containing highly unsaturated impurities (acetylenes such as phenylacetylene, and diolefins) is hydrogenated in the presence of a hydrogenation catalyst preferably containing a platinum group metal as a catalyst component by using a gaseous fraction produced in dehydrogenation reaction as a hydrogen source preferably under >=1kg/cm G- G hydrogen partial pressure at 100 deg.C-room temperature to readily remove the impurities in high hydrogenation selectivity with a little consumption of useful components such as styrenes by hydrogenation and whereby to advantageously obtain purified styrenes suitable for producing a polymeric product of a stable quality having little variation of polymerization characteristic.