The aim of the research are-> 1) to study and analizye the shift of legislative authority prior to and after the amandement of the Indonesian constitution 1945 (uud 1945). 2) to analize some factors which urge the shift of legislative authority prior to and after the amandement of Indonesian constitution 1945 and 3) to formulate an ideal legislative authority based on the Indonesian constitution 1945. Prior to the amandement of the constitution, legislative authority was dominated by assembly the president. While after the amandement the Indonesian legislative dominates the authority. Based on that, the research is conducted to find out whether there is a shift of legislative authority, the factor which urge the shift and what ideal legislative authority based on the Indonesian constitution is like. It is a prescriptive and normative study which is to find out arguments and new concepts prescribed to solve problems mainly dealing with legislative authority. There are three main data namely 1) primary law material (the Indonesian constitution prior to amandement and the Indonesian constitution after the amandement). 2) Secondary law material (treatise of peoples consultative council session dealing with the amandement, related researchers and references). 3) Tertiary law material (any materials related to previous material). Library research and documentation were employeed to collect the data. The data were analized deductively concerning the grammatical interpretation of law. The results of study show that: 1) the amandement of the Indonesian constitution concerning legislative authority is subject to sections subsection 1. It is aimed to strengthen the authority and roles of the Indonesian legislative assembly. 2) the amandement remarks a shift of legislative authority. 3) philosophical, political, yuridicial, sociological, and historical factors urge the shift of the authority (from the president to the Indonesian legislatif assembly. 4) An ideal legislative authority based on the Indonesian constitution is an authority that enables to realize the national ideal basing on the five principles (Pancasila) and to create regulations that fulfill philosophical, political yuridicial, sosiological, and technical planning substances.