Passports, ID Cards, Visas & Entry Formalities for Ireland
Visas are not required by citizens of most Western countries including the USA, Canada, Australia, South Africa, Japan, etc (see below for a full listing of countries whose citizens do not require visas to enter Ireland). Passports are not required for citizens of the European Union - a national identity card will suffice. There are no customs formalities on traffic arriving from other EU states unless the journey originated outside the EU.
For further information Department of Foreign Affairs
Austria in Ireland
Canadian Embassy/l'Ambassade du Canada
Royal Danish Embassy
Royal Norwegian Embassy