The 1st Manchurian Army (Russian: 1-я Маньчжурская армия / 1 МА) was a field army of the Russian Empire that was established in 1904 during the Russo-Japanese War, for the purposes of operating in the Manchuria region against Japan.

It was one of the three such armies that were created and was involved in every major engagement.

It was formed in October–November 1904, from the basis of the Manchurian Army that had existed until September of that year, which had been dissolved after the Battle of Liaoyang.

It consisted of the following formations: 1st Siberian Army Corps primarily as the southern detachment and the 3rd Siberian Army Corps primarily as the eastern.

[1] The 1st Manchurian Army consisted of the following units, as of January 1905.