The study entitled “Legislation Function According to the 1945 Constitution (Case Study of the Legislative Body of the House of Representative to Republic of Indonesia (DPR-RI) for the period 2004-2009”) was made with the purpose to determine the implementation of the DPR-RI's legislative function for the 2004-2009 period, the process of drafting national legislation for the 2004-2009 period, the inhibiting factors in the process of making national legislation programs, efforts to overcome them, and the principles of establishing legislation. The research is based on normative law research that is prescriptive and technical. The research approach uses a legal approach and case approach. The type of research data is secondary data with primary legal material. Data collection techniques in the form of literary studies and data analysis techniques.