Methodology to prepare highly transparent sulfur-vulcanized rubber was investigated. Among various types of rubber, high cis-butadiene rubber (BR) was chosen, and its vulcanization was carried out using variety of rubber chemicals and compounding recipe to maximize the transparency of the vulcanizates. It came to be clear that transparency was affected by the type of sulfur and accelerator used. The composition of the mixed accelerator also influenced the transparency. On the other hand, hardness of rubber vulcanizates depended on the vulcanization temperature. As the results, the BR’s vulcanizates cured by sulfur with high transparency and excellent physical properties has been obtained by the optimization of the compounding conditions. The resulting vulcanizate showed almost the same transparency as the vulcanizate cured by peroxide.