To obtain a magnesium alloy porous body having uniform and fine pores.

The method for producing a magnesium alloy porous body includes: a stage where a magnesium molten metal essentially consisting of magnesium and containing hydrogen of ≥15 ppm is melted, so as to be prepared; a stage where a hydrogen solubility control element-particulate composite material composed of a 5 to 40 wt.% element for controlling hydrogen solubility to magnesium to increase the amount of foaming gas, and ≤6.2 wt.% particulates composed of at least one selected from the particles of carbide, boride, oxide and nitride is added to the magnesium molten metal, and, stirring is performed, so as to prepare an Mg-hydrogen solubility control element-particulate alloy molten metal; and a stage where, in the process of cooling and solidifying the Mg-hydrogen solubility control element-particulate alloy molten metal, hydrogen in the molten metal is foamed to form foam in the magnesium alloy.