Ternary Mg-Zn-Y alloy sheets with several volume fractions of a Mg₁₂ZnY phase were prepared by hot-rolling at 623 K. Volume fraction of the Mg₁₂ZnY phase was increased with increasing of Zn and Y contents in the Mg_100−x−yZn_xY_y (x=1∼6, y=2∼9 at%) alloys, and achieved more than 85% in an Mg₈₅Zn₆Y₉ alloy. (002) pole figures showed both of basal planes of the Mg₁₂ZnY and Mg phases have a tendency to incline toward parallel to the sheet surface. However, it was considered that the formation of a basal plane texture in the Mg₁₂ZnY phase is difficult compared with that in the Mg phase, due to a kink deformation. An Mg_90.5Zn_3.25Y_6.25 alloy sheet exhibited a 0.2% proof strength, an ultimate tensile strength, and an elongation of 353 MPa, 400 MPa, and 5%, respectively, at room temperature, and 279 MPa, 375 MPa, and 12%, respectively, at 523 K. Although elongation was slightly less than those in the commercial Mg sheets, the Mg_90.5Zn_3.25Y_6.25 alloy sheet showed high strength over a wide temperature range compared to those in commercial Mg alloys.