This study is to consider the ideology of state affairs and science-technology leadership of successive governments from President Kim Young-sam till Lee Myung-bak in democratic period. For this consideration, this research carried out the comparative analysis of history on the basis of literature survey. As a result of this research, there was connection between the ideology of state affairs and science-technology leadership of successive governments in democratic period. In particular, the realization of president on science and technology affected science-technology leadership. To reinforce global competitiveness through science-technology innovation is period trend in modern society. Thus, the strong passion of president on science-technology innovation is decisive variable in determining science-technology development. President should show up science-technology leadership on the basis of reasonable judgement on science and technology. Now the leadership of science and technology which can adjust domestic and international interests related to science and technology and solve the conflicts of science and technology will be very important. We must set up systematical and consistent deciding process of science-technology policy. And we have to enlarge aiding organization for the policy of science and technology.