The twenty-three special wards of Tokyo, Japan, divide the central and most populous part of Tokyo into self-governing municipalities. This type of administrative division is unique to Tokyo. Though their formal name is 特別区 (tokubetsuku, "special wards"), they are commonly known in Japan as nijūsanku, "twenty-three wards".

They are special because although they are autonomous with each having a local government, they must at the same time function seamlessly together as one large urban entity in central Tokyo. To this end, certain public services are handled by the Tokyo Metropolitan Government instead of the individual ward. They include the water supply system, sewage disposal, and fire services.

To finance the joint public services provided to the twenty-three wards, the metropolitan government levies some of the taxes that would normally be levied by city governments, and also makes transfer payments to wards that cannot finance their own local administration.

The word "special" distinguishes them from the wards (区 ku) of other major Japanese cities. Before 1943, the wards of Tokyo City were no different from the wards of Osaka or Kyoto. In 1943, when the Tokyo city government and prefectural government merged into a single metropolitan government, the wards were placed under the direct control of the metropolis.


Since the 1970s, the special wards of Tokyo have exercised a considerably higher degree of autonomy than the wards in other cities, making them more like independent cities than districts. Each special ward has its own elected mayor (区長; kuchō) and assembly (区議会 kugikai).

In 2000, the National Diet designated the special wards as local public entities (地方公共団体 chihō-kōkyō-dantai), giving them a status similar to cities. Since then, they have been calling themselves "cities" instead of wards in English, even though the Japanese designation of "ku" is unchanged. They have also taken over certain public services metropolitan government such as garbage collection and disposal.

The wards vary greatly in area (from 10 to 60 km²) and population (from less than 40,000 to 830,000). Setagaya has the most people, while neighboring Ōta, the largest area.

The total population of the twenty-three special wards was 8,483,140 as of October 1, 2005 *, about two-thirds of the population of Tokyo and a quarter of the population of the Greater Tokyo Area. The twenty-three wards have a population density of 13,800 per square kilometre (35,600 per square mile).