In this diploma thesis, we were interested in the importance of external factors or actors for the democratization of post-socialist countries. The biggest focus was on the democratization processes in Poland and Hungary, where the influence of the European Union was most visible. We were interested how and with which mechanisms did the EU, as an example of an external actor, transform the process of democratization in the analyzed countries. Democratization is a process of transitioning from a nondemocratic regime to a more democratic one. This raises the question of what is democratic and what is democracy itself. Theoretical considerations lead us to the final conclusion about the importance of liberal democracy in modern countries and the international community. The desire to reduce the number of conflicts, and peaceful trade between countries is high on the agenda of liberal democratic countries. In essence, we divide democratization factors on to internal and external. The first to emphasize the importance of external factors was Huntington in the early nineties. The authors describe the role and significance of external actors in terms of promoting democracy. They split the manner of influencing on the process of democratization in two main groups - the economic and the political sphere. We tried to measure the EU's influence on Poland and Hungary by the quantity of interactions between the EU and the analyzed countries on the basis of public announcements from the European Commission between 1985 and 1994, and found that most of the cases were for interaction at the economic level, and only a few percent were at political level. An important role for democratization in both countries was played by the EU Program, PHARE, which in the early 1990s greatly helped Poland and Hungary to transition to a democratic regime and a market economy.