A method for producing a high-strength magnesium alloy material includes (a) a step of preparing a magnesium alloy workpiece having a top face and a side face; and (b) a step of applying a compressive load σp (MPa) from the top face side of the workpiece and performing a uniaxial forging process on the workpiece. Step (b) is performed while suppressing deformation of the workpiece widening outward and under conditions including (i) σp>σf (where σf is the compressive breaking stress (MPa) of the workpiece); (ii) a plastic deformation rate is less than or equal to 10%, and (iii) a strain rate is less than or equal to 0.1/sec.