This article examines and identifies the cause of the legislative gridlock on a medical law amendment related to the Lee Myung-bak administration's medical privatization policy. Although the medical privatization policy is a representative policy that generates conflicts and gridlocks, the analysis on elements of legislative gridlocks has not been investigated. Therefore, this study analyzes the impacts of the characteristics of each Member of Parliament, partisan and institutional factors, factors related to proposers of the legislation, and alliance factors of political actors on the gridlock focusing on the 2010 medical law amendment case during the Lee Myung-bak administration. The analysis results are as follows. Parliamentarian characteristics such as the first election, proportional representation, and parliamentary origin affected the legislative gridlock. In addition, factors such as the operating process of the standing committee, government submission bill, and alliance with political actors influenced the legislative gridlock of the medical law amendment. In the case of the issue bill, it implies that it is necessary to prepare reasonable alternatives through close communication and consultation with the government as well as the National Assembly, and policy coordination with various political actors.