The Department of Magical Law Enforcement is the largest department at the Ministry of Magic, although the Department of Mysteries' size is unknown. 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. Harry joined this department, under the Aurors' Office, at the age of seventeen and was followed by Ron Weasley. It includes the following known offices:
¡Auror Office (Harry Potter becomes the Head of the office in 2007)
¡Department of Intoxicating Substances
¡Improper Use of Magic Office
¡Misuse of Muggle Artefacts Office
¡Office for the Detection and Confiscation of Counterfeit Defensive Spells and Protective Objects
¡Wizengamot Administration Services

Moderator: Hermione Granger

The Department of Magical Accidents and Catastrophes is responsible for repairing accidental magical damage. It includes these known departments:
¡Accidental Magic Reversal Squad
¡Obliviator Headquarters
¡Muggle-Worthy Excuse Committee
¡Invisibility Task Force
¡Muggle Liaison Office

Moderator: Hermione Granger

The Department for the Regulation and Control of Magical Creatures is the second largest Department in the Ministry. After leaving Hogwarts School of Witchcraft and Wizardry, Hermione Granger briefly worked in this department before transferring to the Department of Magical Law Enforcement. It includes these known departments:
¡Beast Division
¡Being Division
¡Spirit Division
¡Goblin Liaison Office
¡Centaur Liaison Office
¡Pest Advisory Board
¡Office of Misinformation

Moderator: Hermione Granger

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.[HP4] 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, though seems to hold less prowess in the Wizarding world, apparently. It includes these known departments:
¡International Magical Trading Standards Body
¡International Magical Office of Law
¡International Confederation of Wizards, British Seats

Moderator: Hermione Granger

The Department of Magical Transportation is responsible for various aspects of magical transport. It includes these known departments:
¡Floo Network Authority
¡Broom Regulatory Control
¡Portkey Office
¡Apparation Test Centre

Moderator: Hermione Granger

The Department of Magical Games and Sports, seen as the most relaxed department (posters for favourite Quidditch teams are found tacked to the walls), deals with organising sports events the likes of the Quidditch World Cup and the Triwizard Tournament. Ludovic Bagman used to be the Head of Department here, but his gambling problem forced him to flee from Goblin creditors. It includes these known departments:
¡ British and Irish Quidditch League Headquarters
¡ Official Gobstones Club
¡ Ludicrous Patents Office

Moderator: Hermione Granger

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

Moderator: Hermione Granger

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.The also rarely talk,even to their co-workers.[9] It includes these 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
¡ The Veil (Inside the Death Chamber)

Moderator: Hermione Granger