The invention offers a magnesium alloy sheet material having excellent plastic processibility and rigidity and a magnesium alloy formed body having excellent rigidity. The sheet material has magnesium alloy that forms the matrix containing hard particles. The region from the surface of the sheet material to a position away from the surface by 40% of the thickness of the sheet material is defined as the surface region, and the remaining region as the center region. Hard particles existing in the center region have a maximum diameter of more than 20 μm and less than 50 μm, and hard particles existing in the surface region have a maximum diameter of 20 μm or less. Because the hard particles existing at the surface side are fine particles, they are less likely to become the starting point of cracking or another defect at the time of plastic processing. Because the hard particles existing in the center region are coarse, they can increase the rigidity of the sheet material.