Social security system has entered into a change especially in the 1980s in many countries after economic and social problems which forced system to change. Especially financial deficits of social security institutions due to aging population emerged as a major problem. The aim of this study is to analyze the reasons which caused the change of social security systems. Even the visible reason is financial problems due to aging population, it is not the only reason. The process of globalization which forces developed economies to take measures against the international competitiveness which became a burden for producers is the major reason.