The Department of the Taoiseach is the government department of the Taoiseach, the title in Ireland for the head of government. It is based in Government Buildings, the headquarters of the Government of Ireland, on Merrion Street in Dublin.

The Taoiseach is the head of government or prime minister of Ireland. The office is appointed by the President of Ireland upon the nomination of Dáil Éireann and the office-holder must retain the support of a majority in the Dáil to remain in office.