Differences in sensory evaluation, physicochemical properties and antioxidant activities between green tea concentrations and tannase-treated green tea concentrations were measured in this study. The results showed that pH did not differ dependent on tannase treatment but antioxidant ability were slightly increased through tannase treatment without significant($p$ <0.05). However, the turbidity of the tannase-treated green tea concentration had significant difference to the non-treated concentration. The astringency, tested via sensory evaluation, decreased significantly after tannase treatment($p$ <0.05). Traces of epicatechin gallate(ECG) and epigallocatechin gallate(EGCG) also disappeared after the tannase treatment, due to the fact that the ester linkages in the catechin structure were broken by the tannase. It was concluded that tannase treatment of tea products is a very effective process for decreasing astringency and turbidity.