Can I travel to Ireland on my Belgian residence card
The Belgian Residence Document (example) issued to EU citizens residing in Belgium, previously referred to as an E/E+ card (example), is not valid for travel outside the Schengen Area. Ireland is not in the Schengen Area and Irish citizens require a valid passport or passport card to travel to Ireland.
Information for Belgian citizens is available here.
Special Identity Cards
The special identity card (example) issued by the Belgian Foreign Ministry to those working in international organisations, such as embassies or the EU institutions, cannot be used for travel to Ireland.