Its purpose was to strengthen the Tokugawa family's domination of the entire country by regulating the power (military force) of the feudal lords; it was focused in particular on the western provinces, where there were a lot of nonhereditary feudal lords.
大名の勢力（軍事力）を統制して徳川家による全国支配を強化することを目的としており、特に外様大名の多い西国に徹底させた。