Waste tire was decomposed in supercritical tetrahydrofuran in a 300 ml batch autoclave reactor. The reaction products were examined by GPC and TG/DTA. TG/DTA thermograms of the waste tire and decomposition product were divided into two regions : First region was due to weight loss by decomposition of SBR, and second region by decomposition of low molecular weight. As the pyrolysis temperature increased from 270 to 320℃, and the reaction pressure increased from 3000 to 4000 psi, the molecular weight of extract was decreased. In this study, the optimum temperature and pressure were 300℃ and 3000 psi, respectively.