The Japan–Korea Treaty of 1905, also known as the Eulsa Treaty, Eulsa Unwilling Treaty or Japan–Korea Protectorate Treaty, was made between the Empire of Japan and the Korean Empire in 1905. Negotiations were concluded on November 17, 1905. The treaty deprived Korea of its diplomatic sovereignty and made Korea a protectorate of Imperial Japan. It resulted from Imperial Japan's victory in the Russo-Japanese War in 1905.

The Korean Empire, officially the Empire of Korea or Imperial Korea, was a Korean monarchical state proclaimed in October 1897 by King Gojong of the Joseon dynasty. The empire stood until Japan's annexation of Korea in August 1910.