The effect of hydrated lime (HL) as an antioxidant (AO) for retarding aging of asphalt mixture using the large molecular size (LMS) of gel-permeation chromatogram (GPC) technique. A HL were used for preparing dense-graded asphalt (DGA) mixes to examine the effect of the HL on age retardation. The asphalt mixtures prepared with and without HL were aged artificially in two stages; the short-term aging (SA) for 1, 2, 4 hour at 160℃ and 180℃ on the loose mixes, and the long-term aging (LA) for 68 hours at 110℃ on the specimen. The specimen ( =100mm) of SA-treated mix was compacted to the air void of 7% using a gyratory compactor. The LMS values were used for estimating absolute viscosity (AV) for evaluating aging level and age- retardation effect in terms of viscosity. It was observed that the asphalt mixes which were short-term aged at 180℃ for over 2 hours were significantly aged, compared with the mix which was short-term aged for 1 hour at 160℃. It was also found that the use of 1.5% HL by wt. of mix resulted in a significant reduction of binder aging of SA and LA treated mixes. It was concluded that the HL did apparently have an effect of reducing aging of asphalt in the mixes after SA and LA. This result will be an applicable information for retarding aging of the field HMA mixture which is carried in the dump truck at hot temperature for 2-4 hours.