An interior ministry is the executive office of a governmental department for internal affairs, as opposed to the external affairs managed by a ministry of state or defense. It usually controls internal policing and security as well as immigration enforcement.

This does not apply to ministries of land management, which may be named in a similar manner (such as the United States Department of the Interior).

The internal-affairs responsibilities establish this use. A similar departmental name is insufficient when the actual responsibility is land management, and a separate immigration office is not itself a ministry solely because it administers part of the ministry's work.