In this study, the leakage current - voltage characteristic and leakage current - time characteristic for the undegradated Ethylene Propylene Rubber and the Ethylene Propylene Rubber which is degradated by water tree for 200 hours have been measured on the temperature range of 50∼80℃ and applied DC voltage range of 200 V∼800 V for 90 minutes. The results of this study are listed below. In case the temperature is 50℃, it founds that the leakage current have shown a increase in proportion to the applied voltage as 2 pA in 200 V, 6 pA in 400 V, 10 pA in 600 V and 15 pA in 800 V. It founds that the leakage current increased with the rise of temperature. It founds that the leakage current was consistent as time goes by, the leakage current of the sample degradated by water tree for 200 hours has increased more than undegradated sample.