Sankin kōtai (参勤交代) was a policy of the shogunate during most of the Edo period of Japanese history. The purpose was to control the daimyo. In adopting the policy, the shogunate was continuing and refining similar policies of Toyotomi Hideyoshi. In 1635, a law required sankin kotai, which was already an established custom. The law remained in force until 1862.

The details changed throughout the twenty-six decades of Tokugawa rule, but generally, the requirement was that the daimyo of every han move periodically between Edo and his han, typically spending alternate years in each place. His wife and heir were required to remain in Edo as hostages. The expenditures necessary to maintain lavish residences in both places, and for the procession to and from Edo, placed financial strains on the daimyo.

In principle, the sankin kotai was a military service to the shogun. Each daimyo was required to furnish a number of soldiers (samurai) in accordance with the assessment of his han. These soldiers accompanied the daimyo on the processions to and from Edo.

With hundreds of daimyo entering or leaving Edo each year, processions (大名行列 daimyo gyoretsu) were almost daily occurrences in the shogunal capital. The main routes to the provinces were the kaido. Special lodgings, the honjin (本陣), were available to daimyo during their travels.

The sankin kotai figures prominently in some Edo period ukiyoe (woodblock prints), as well as in popular theater such as kabuki and bunraku.