The Japan Sumo Association (Japanese: 日本相撲協会, Hepburn: Nihon Sumō Kyōkai), officially the Public Interest Incorporated Foundation Japan Sumo Association (公益財団法人日本相撲協会, Kōeki zaidanhōjin Nihon Sumō Kyōkai); sometimes abbreviated JSA or NSK, and more usually called Sumo Kyōkai, is the governing body that operates and controls professional sumo wrestling, called ōzumō (大相撲), in Japan under the jurisdiction of the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT).

Concretely, the association maintains and develops sumo traditions and integrity by holding tournaments and tours. The purposes of the association are also to develop the means dedicated to the sport and maintain, manage and operate the facilities necessary for these activities. Therefore, the JSA operates subsidiaries such as the Kokugikan Service Company to organize its economic aspects, the Sumo School to organize training and instruction or the Sumo Museum to preserve and utilize sumo wrestling records and artefacts.

Though professionals, such as active wrestlers, referees, hairdressers and ushers, are all on the association's payroll, leadership positions are restricted to retired wrestlers. The organization has its headquarters in the Ryōgoku Kokugikan arena, in Sumida, Tokyo.

The association's culture is based on respect for the law and continuity of sumo's traditions, deeply rooted in Japan's history and Shinto religion. It has a reputation for secrecy. In response to a number of scandals, the association has implemented numerous reforms in recent decades.

The association has its origins in a Shinto ritual (or festival) that has been held since ancient times to pray for a bountiful harvest. This primary form of sumo was called shinji-zumō (神事相撲). During the Sengoku period, Oda Nobunaga made sumo a popular sport, aided by the emergence of large cities (like Edo, Osaka, Sendai and Nagoya), which soon began to compete with Kyoto's cultural monopoly, as it was Japan's only metropolis at the time. These new cultural centres saw the emergence of wrestling groups, from both the commoners and the warrior classes, who took part in festivities at shrines. During the Edo period, sumo bouts, called kanjin-sumo (勧進相撲), were often held to raise funds to develop provinces (new construction or repair of bridges, temples, shrines and other public buildings) or for entertainment purposes.

After the Sengoku period, during the period of peace established under the Tokugawa shogunate, Japan experienced an unprecedented period of vagrancy for many samurai who had lost their social standing (called rōnin). These masterless samurai, began to be organized in two extremes that coexisted side by side. On the one hand, certain powerful clans formed suites of wrestlers organized into veritable royal households called geisha-gumi (芸者組; lit. 'geisha troupe'), and elevated them to the status of vassals. On the other hand, a number of rōnin had no choice but to put their martial skills to good use in street sumo tournaments, called tsuji zumō (辻相撲, tsuji-sumo; lit. 'street-corner wrestling'), for the entertainment of passers-by. Similarly, a number of street entertainment wrestling groups formed and began touring, sometimes with the support of shrines that occasionally recruited them as part of religious festivities and to help priests raising money for the construction of buildings. Eventually, this mix of professional wrestlers and disgraced rōnins, along with the commoners who took part in the contests of strength of the street tournaments, created conflicts over money. Tense brawls, even deaths, sometimes occurred. Public order became so disturbed that in 1648 the Edo authorities issued an edict banning street sumo and matches organized to raise funds during festivities. Over the next two decades or so, the wrestlers, now without any income, decided to petition the authorities to lift the bans, forming informal associations that resembled coalitions of interests to protect themselves from any violent repression of their movement. In 1684, these movements bore fruit and a rōnin by the name of Ikazuchi Gondaiyū (雷 権太夫) obtained permission to hold a tournament after proposing a new etiquette associated with tournaments. The organization of tournaments began to depend more on groups following new standards designed to satisfy the authorities of the towns hosting them. These associations gradually came to depend on the influence of retired former wrestlers who began to organize tournaments.

At that time, the Edo-based association (although composed of elders as today) was organized in such a way as to be dominated by a duo of executives, the fudegashira (筆頭), the director, and the fudewake (筆別), his second. The composition of the banzuke and its hierarchy was primarily their decision, and conflicts of interest were common. In addition, the profits from the tournaments were first divided among them before a portion was given to the other elders, who in turn distributed the money to their disciples. Because of the filtering of high-ranking managers, little money reached the bottom of the ladder, and this system was only tolerated because the patronage of local lords also added extra salaries for high-ranking wrestlers.

Wrestlers who took part in these authorised tournaments without the patronage of lords did not yet have samurai status or a salary and their finances depended largely on donations they could receive from the organisers of charity tournaments or admirers. The organisers also ensured that they were fed and housed for the duration of the tournament. In those days the promotion system was decided by the tournament organisers, who then distributed the profits to the elders who then redistributed funds to their wrestlers, with the wrestlers under the protection of the lords receiving bonuses and having financial security and the others being kept in a situation of poverty. In 1757, during the Hōreki era, the beginnings of the Japan Sumo Associations were formally established as Edo Sumō kaisho (江戸相撲会所, Edo Sumo Club), later called Tokyo-zumō kaisho. In 1869, the Ōsaka Sumō Kyōkai (大坂相撲協会, Osaka Sumo Association) was founded. Each associations had their own history and changes. For example, from 1888 to 1895 the Kōkaku-gumi (廣角組), led by wrestlers Ōnaruto and Shingari, broke off from Osaka-sumo. In 1897, these movements led to reforms in the Osaka-based association, which became the Ōsaka Sumō Kyōkai (大阪角力協会, Osaka Wrestling Association).