Most of technology information obtained from KSLV-I program have been managed by Program Life-Cycle Management System(PLMS). As involving technologies in the program require high level of confidentiality as those may be dealt with entities in international cooperation, the enforcement of strict security policy is inevitable. Therefore, a document security system has been developed to enhance protection in document management. This paper describes the overview and development status of the security system, integrated with PLMS, which aims at preventing illegal access and inadvertant leakage of the technology information.