An interior ministry (sometimes ministry of internal affairs or ministry of home affairs) is a government ministry typically responsible for policing, emergency management, national security, supervision of local governments, conduct of elections, public administration and immigration matters. The ministry is often headed by a minister of the interior or a minister of home affairs. In some countries, matters relating to the maintenance of law and order and the administration of justice are the responsibility of a separate justice ministry.

The United States Department of the Interior (DOI) is the United States federal executive department of the U.S. government responsible for the management and conservation of most federal land and natural resources, and the administration of programs relating to Native American, Alaska Natives, Native Hawaiians, territorial affairs, and insular areas of the United States. About 75% of federal public land is managed by the department, with most of the remainder managed by the Agriculture department's United States Forest Service.