OPECST (Office parlementaire d’evaluation des choix scientifiques et technologiques) helps decision making of the French Parliament by assessing options of scientific and technological policy. In this process, OPECST holds public hearings and gathers opinions from various participants: experts, industry, citizens, and so on. It held many public hearings and assessments on nuclear energy policy in the 1990s, when French people started to demand more transparency and independence of the nuclear safety regime than before. So we can assume that OPECST helped the reform in the 1990s and in the 2000s that finally established the Law on Transparency and Security in the Nuclear Field. This research aims to precisely clarify its function through a survey of all the reports of OPECST on nuclear safety policy published in this period and of political decisions related to them. As a result, it is shown that the function of OPECST consists of three elements: it defines problems, elaborates policy recommendations from various opinions, and accumulates its survey results in the form of reports. Nowadays, the form of the discussion carried out by OPECST is changing, so we have to learn both its history and recent activities to make a policy-making system that would be suitable in Japan.