The single currency, the Euro, was introduced to the market in twelve member states of the European Union (EU) on 1 January 2002. Denmark, Sweden, and UK are still outside the ‘Euroland’. Among the three countries, Denmark held a referendum to introduce the Euro on 28 September 2000, but the government proposal was rejected by 46.8% to 53.2% then. According to the governments of Sweden and UK, the both countries will also hold a referendum on this topic in the near future. The purpose of this paper is to analyse the Euro referendum in Denmark and to examine why the majority of the Danes rejected the government proposal. It has two important points for research on the EU. Firstly, the Euro was introduced in most of the member states as previously scheduled, but this was a controversial issue in domestic politics and there was anxiety about the Euro among the people. The referendum in Denmark clearly shows the attitudes of the government, political parties, interest groups, and the people towards the Euro. This will lead to analysis of anti-Euro sentiments in the EU, which can be seen especially in Sweden and UK. Secondly, this case of Denmark will be a good example to analyse the future integration of the EU. Deepening the integration has resulted in serious polarization of the member states. This has two aspects; member states and the people in each member state that are keen or reluctant to deepen the integration. It is essential for the EU to overcome these difficulties of polarization. This problem will be more and more important in an enlarged EU. Membership of the 10 countries in 2004 will expand a diversity of integration plans of the EU, especially scope and speed of integration. In conclusion, the people in Denmark had difficulties in coordinating the two identities; national identity and European identity. The Danish currency, crown (krone), was regarded as a symbol to maintain national identity of Denmark and Danish way of life. This is very closely connected with the future of the Danish welfare state. Based on this anxiety, the majority of the Danes said No to the Euro at the referendum, although only small parties like Danish People's Party and Socialist People's Party voted against the Euro at the national parliament. The Euro problem reminds us that it is of importance for the EU to get support from the people and that deepening. the integration is closely linked to domestic politics of the member states.