The Order to expel barbarians was an edict issued by the Japanese Emperor Kōmei in 1863 against the Westernization of Japan following the opening of the country by Commodore Perry in 1854. The edict was based on widespread anti-foreign and legitimist sentiment, called the Sonnō jōi "Revere the Emperor, Expel the Barbarians" movement. Emperor Kōmei personally agreed with such sentiments, and – breaking with centuries of imperial tradition – began to take an active role in matters of state: as opportunities arose, he fulminated against the treaties and attempted to interfere in the shogunal succession.

The Shogunate had no intention of enforcing the order, and the Edict inspired attacks against the Shogunate itself as well as against foreigners in Japan. The most famous incident was the firing on foreign shipping in the Shimonoseki Strait off Chōshū Province as soon as the deadline was reached. Masterless samurai (rōnin) rallied to the cause, assassinating Shogunate officials and Westerners. The killing of the English trader Charles Lennox Richardson is sometimes considered as a result of this policy. The Tokugawa government was required to pay an indemnity of a hundred thousand British pounds for Richardson's death.

But this turned out to be the zenith of the sonnō jōi movement, since the Western powers responded to Japanese attacks on western shipping with the Bombardment of Shimonoseki. Heavy reparations had earlier been demanded from Satsuma for the murder of Charles Lennox Richardson – the Namamugi Incident. When these were not forthcoming, a squadron of Royal Navy vessels went to the Satsuma port of Kagoshima to coerce the daimyō into paying. Instead, he opened fire on the ships from his shore batteries, and the squadron retaliated. This was later referred to, inaccurately, as the Bombardment of Kagoshima. These incidents clearly showed that Japan was no match for Western military might, and that brutal confrontation could not be the solution. These events, however, also served to further weaken the shogunate, which appeared too powerless and compromising in its relations with Western powers. Ultimately the rebel provinces allied and overthrew the shogunate in the Boshin War and the subsequent Meiji Restoration.