The Sakuradamon Incident was the assassination of Ii Naosuke, Chief Minister (Tairō) of the Tokugawa shogunate, on March 24, 1860 by rōnin samurai of the Mito Domain and Satsuma Domain, outside the Sakurada Gate of Edo Castle.

Ii Naosuke was a daimyō of Hikone (1850–1860) and also Tairō of the Tokugawa shogunate, Japan, a position he held from April 23, 1858, until his death, assassinated in the Sakuradamon Incident on March 24, 1860. He is most famous for signing the Harris Treaty with the United States, granting access to ports for trade to American merchants and seamen and extraterritoriality to American citizens. He was also an enthusiastic and accomplished practitioner of the Japanese tea ceremony, in the Sekishūryū style, and his writings include at least two works on the tea ceremony.