The Department of Magical Law Enforcement is the largest department at the Ministry of Magic. Arguably the most important of the various departments, it is a combination of police and justice facilities and is roughly the equivalent to the Home Office of Muggle Britain or the Department of Justice in the United States.

It includes the following departments:

The Department of Magical Accidents and Catastrophes is responsible for repairing accidental magical damage. It includes the following known departments:
* Accidental Magic Reversal Squad
* Obliviator Headquarters
* Invisibility Task Force

The Department for the Regulation and Control of Magical Creatures is the second largest Department in the Ministry. It includes the following known departments:
*Dangerous Creature Overwatch
* Ministry-Employed Dragonologists
* Werewolf liaison Offices
* Intelligent Magical Creature Liaison Office

The Department of International Magical Cooperation is an agency concerned in foreign affairs that attempts to get wizards from different countries to cooperate in wizarding actions both political and public. The former head was Bartemius Crouch Sr., until his death. This is also where Percy Weasley began his Ministry career. It is closest to the Muggle British Foreign & Commonwealth Office and the US State Department. Though it once held less prowess in the Wizarding world, now it's starting to pick up steam. It includes the following known departments:
* International Magical Trading Standards Body
* International Magical Office of Law
* International Confederation of Wizards, British and foreign Seats

This department houses the Floo Network Authority, Broom Regulatory Control Agency, Portkey Authority, & Apparition Testing Center. This department also is responsible for the maintenance of the Hogwarts Express train as well as the Knight Bus.

The Department of Magical Games and Sports, seen as the most relaxed department (posters for favorite Quidditch teams are found tacked to the walls), deals with organizing sports events the likes of the Quidditch World Cup and the Triwizard Tournament. The occasional bludger may be loose in the office, so watch out!

The Atrium is an area that serves to welcome visitors to the Ministry of Magic.
* Lobby and Reception Area
* Fountain of Magical Brethren/Magic is Might Monument
* Security Desk
* Lifts
* Magical Maintenance Office

The Department of Mysteries is a section of the Ministry of Magic that carries out confidential research. Most of its operations are carried out in total secrecy. Few wizards within the Ministry actually know what is located within this department. Those wizards who work in the Department of Mysteries are known as Unspeakables because of the confidential nature of their work. It includes the following known chambers:
* Hall of Prophecies
* The Death Chamber
* The Thought Chamber
* The Time Chamber
* The Space Chamber
* The Love Chamber a.k.a. The Ever-Locked Room