The Iwakura Mission project came up before the completion of Haihan-chiken (abolition of feudal domains and establishement of prefectures) that had been set about on August 29, 1871, in the project Tomomi IWAKURA, Toshimichi OKUBO, Takayoshi KIDO and many other leaders of the Meiji government finally joined the great delegation, and therefore the Establishment was organized by Grand Minister Sanetomi SANJO at its head, Takamori SAIGO, Kaoru INOUE, Shigenobu OKUMA, Taisuke ITAGAKI, Shinpei ETO and Takao OKI in order to protect the nation and to settle the affairs of Haihan-chiken while the Iwakura Mission was traveling abroad officially.
明治4年7月14日(旧暦)（1871年8月29日）に断行された廃藩置県の後始末が済まないうちに、岩倉使節団の計画が持ち上がり最終的に岩倉具視・大久保利通・木戸孝允ら明治政府を主導してきた首脳の多くが加わる一大使節団となったことから、使節団の外遊中の留守を守るとともに廃藩置県の後始末を行うための組織として太政大臣三条実美を筆頭に西郷隆盛・井上馨・大隈重信・板垣退助・江藤新平・大木喬任らによって結成された。