At present the EU is experiencing a drastic increase in the flow of immigrants. The European continent and the African and Asian Continents are only separated by the Mediterranean Sea. The majority of immigrants go to Europe by crossing the Mediterranean Sea. The Mediterranean route is divided into 3, namely: the Eastern Mediterranean Route, the Western Mediterranean Route, and the Central Mediterranean Route. The Central Mediterranean Route is the most dangerous route evidenced by the highest mortality rate compared to other Mediterranean Sea routes. However, the Central Mediterranean Route is the most popular route for immigrants, especially immigrants from Libya or Tunisia. On June 22, 2015, the European Union collaborated with the Libyan Government to form an operation called the Mediterranean European Union Naval Force or commonly known as Operation Med Eunavfor. The core task of this mission is to make a systematic effort to identify, capture, and dispose of ships suspected of being used by immigrant smugglers or traffickers, and this operation also contributes to anticipating the many casualties that have fallen on the Mediterranean Sea. However, on July 4, 2017, the European Union issued a report stating that Operation Med Eunavfor had failed in carrying out its mission. This study used qualitative wethod, and provides data taken from printed or e-books, journal, documents, papers, and websites. By using “theory of regime effectiveness” coined by Arild Underdall, this study reveals the factors of Mediterranean European Union Naval Force Operation ineffectiveness while decrese immigrants to Europe.