EU Member States ( English : The European Union Member State of ) is a country in the 28 countries that joined the EU. Since the founding of the European Coal and Steel Community ( ECSC ), the country was originally founded, with only six member countries, which was expanded to a total of six times, once the largest born. 1 May 2547 , with the state members attended more than 10 countries of the European Union consists of 21 countries. Republic , six kingdoms , and one Grand Duchy