Every year, a large amount of domestic polystyrene wastes are thrown out. So, the importance of recycling of these resources is facing a big environmental issue. There are several methods for recycling polystyrene wastes: chemical recycling, material recycling, etc. Among them, chemical recycling can be a promising technology to deal with many problems caused by a disposal of the polystyrene wastes. In this paper, patents on chemical recycling technologies were analyzed from the view points of economy and efficiency. Range of the search was limited to patents opened in U.S.A. (US), European Union (EP), Japan (JP), and Korea (KR) from 1987 to 2006. Patent trends in the field of chemical recycling were analyzed by the years, countries, companies, and technologies.