In this thesis, the political economy of the military spending of the member states of the European Union is investigated. The paper aims to analyse how political, economic and security factors influence decisions on military spending in the EU, and how this spending is reflected in more comprehensive economic and political processes in the EU. The paper uses a mixed methodology, which includes a quantitative analysis of data on military spending and other relevant variables such as GDP per capita, trade balance, and several indices taken from the Varieties of Democracy V-DEM such as the corruption index and fragmentation index, World bank (political orientation of the ruling party) and the globalisation index from KOF, as well as a qualitative analysis of relevant literature and documents. Special attention is paid to the political and economic factors that influence military spending decisions, including security challenges, the current state of the economy, public pressure, and the influence of international institutions such as the NATO pact. The results of the research show that there are significant differences in the military spending of the EU member states and that political and economic factors have an influence on these differences. The influence of GDP and trade balance proved to be the greatest, while indicators of the quality of democracy proved to be significant, but of little value. Based on these results, the paper concluded that many different variables and determinants determine the level of military spending by EU member states. Further recommendations for determining military policies in the European Union can be made using these results.