Which is not a principal organ of the United Nations?

International Monetary Fund

International Monetary Fund is not a principal organ of the United Nations.

The United Nations (UN) has six main organs. Five of them — the General Assembly, the Security Council, the Economic and Social Council, the Trusteeship Council and the Secretariat — are based at UN Headquarters in New York. The sixth, the International Court of Justice, is located in The Hague in the Netherlands.