PURPOSE: To provide a method for determining solid solution manganese which can accurately measure the solid solution manganese in aluminum sample.

CONSTITUTION: A sample consisting of aluminum or aluminum alloy is dissolved by phenol under heating, it is diluted by benzyl alcohol, it is separated into solid and liquid for sampling phenol/benzyl alcohol mixed liquid solution where solid solution manganese is dissolved, citric acid aqueous solution is added to the mixed liquid solution for causing the solid solution manganese to migrate to the water phase side of the citric acid aqueous solution. and then manganese migrating into the water phase is determined. thus determining the solid solution manganese in the aluminum sample accurately and controlling the quality of various kinds of products made of aluminum or aluminum alloy accurately and easily.