The Japan Sumo Association (日本相撲協会 or Nihon Sumo Kyokai) is the body who operate and control professional sumo wrestling in Japan.

Membership is by puchasing, or inheriting a share in the association, of which there are 105. The value of these shares is extremely high and rules only permit them to be purchased by former sumo wrestlers who either reached at least a sanyaku rank (komusubi and higher) or been ranked for a significant number of tournaments as a sekitori. Each share is associated with a particular name and in the sumo world the former wrestler will be known by that name, usually with the suffix oyakata. The members are also often called elders in English.

An exception to the purchase requirement is made for the most successful former yokozuna who may be offered a one-time membership of the Association. Three former wrestlers, Taiho, Kitanoumi and Takanohana obtained this status. A fourth, Chiyonofuji, was offered this status but preferred a normal share. These four all achieved more than twenty tournament championships in their active career.

The members of the Association receive a salary and are expected to assist in the running of the association, from selling tickets at the most junior level, to taking charge of one of the Association Departments as a director.

The members are also the only persons able to train new sumo wrestlers. They do this by opening a training stable, or heya (changed to beya as a suffix) which will go by the membership name they own. Thus Dewanoumi-oyakata will be the owner of Dewanoumi-beya. Typically about 50% of the Association members have their own stable, while the rest are affiliated to one and assist the prinicpal owner. It is common for the most senior members of the Association to concentrate on their association responsibilities and pass the chief running of a stable to another. In doing this the two members may elect to swap names so that the stable can keep the more prestigious name.

The Association Members are also split into various ranks. A new retiree will have oyakata rank, except for former Ozeki and Yokozuna who are automatically granted Committee Member rank. Most experienced Association members are Committee Members. At the top are a group of elected riji or directors, who form the Association Board. The public face of sumo is presented by chairman of the directors, called the rijicho. He is effectively President of the Association.

All members are required to retire when they reach the age of sixty five, after which they can sell or pass their stock to another, provided that person meets the association's eligibility requirements.