PURPOSES : This study is aimed at developing an asphalt pavement material with high elasticity and watertight through mix design and laboratory tests. METHODS: High elastic (HE) asphalt modifier blended of thermoplastic elastomer, naphthene oil, mineral fiber and organic vulcanization accelerator was developed. Mix design was done to determine the aggregate gradation and optimum asphalt content for making high elastic and watertight asphalt mixture. Performance grade test of HE-modified asphalt binder as well as asphalt mixture tests, which include the tensile strength ratio test, Hamburg wheel tracking test, third-scale model mobile loading simulator(MMLS-3) test, four-point flexural fatigue test, and Texas reflection crack test were conducted to evaluate the characteristics of the HE-modified asphalt mixture. RESULTS: 7.7% optimum binder content was determined through the mix design, which met the quality criteria of Marshall asphalt mixture. The binder test indicated that the grade of the HE-modified asphalt was PG76-28. The results of the mixture tests indicated a tensile strength ratio of 0.92 and a rut depth of 6.2 mm at 20,000 cycles of Hamburg Wheel-Tracking Test. The asphalt mixture test also showed that the rut depth of HE-modified mixture was 39% less than that of Guss asphalt mixture. The crack resistance of the HE-modified mixture was 1.65 times higher than that of the Guss asphalt mixture from the Texas reflection crack test results. CONCLUSIONS: It can therefore be reasonable that HE-modified asphalt mixture is used as an intermediate layer in the asphalt overlay on concrete pavements. Additionally, the HE-modified asphalt mixture can be used for the asphalt pavement materials with high performance and watertight.