Disclosed is a magnesium alloy material having excellent tensile strength and favorable ductility. Therefore, the magnesium alloy sheet material formed by rolling a magnesium alloy having a long period stacking order phase crystallized at the time of casting includes in a case where a sheet-thickness traverse section of an alloy structure is observed at a substantially right angle to the longitudinal direction by a scanning electron microscope, a structure mainly composed of the long period stacking order phase, in which, at least two or more αMg phases having thickness in the observed section of 0.5 μm or less are laminated in a layered manner with the sheet-shape long period stacking order phase.