To provide a method for producing a magnesium alloy ingot with which the ingot having fine and dense structure can be produced, regardless of this alloy composition.

The method for producing the magnesium alloy ingot is provided with; a casting process for casting molten magnesium alloy into a metallic mold; and a cooling process for making flow of cooling gas into a gap between the metallic mold and a solidified shell after generating the solidified shell on the most outer surface of the molten magnesium alloy. In this case, this cooling gas is desirable to use a mixed gas of an inert gas and a non-firing gas.