METAL REMOVAL AGENT

A metal removal agent used when removing Mg from an aluminum alloy melt whose raw material is scrap or the like and used for formation of a molten salt layer that takes in Mg from an aluminum alloy melt. The metal removal agent contains: a specific metal element one or more of Cu, Zn, or Mn; a specific halogen element one or more of Cl or Br; and Mg. The metal removal agent may also contain: a base halide that serves as a base material of the molten salt layer; and a specific metal halide that is a compound of a specific metal element and a specific halogen element. When the molten salt layer formed using the agent and the aluminum alloy melt containing Mg are brought into contact with each other, Mg is taken into the molten salt layer side from the aluminum alloy melt side and efficiently removed.