Provided is a method for producing a zinc alloy, which enables the production of a Zn-Si alloy having a uniform composition. Metal Zn is melted in a crucible (2) arranged in a heating furnace (1) to produce molten Zn (4). The floating of a metal Si powder (6) added to the molten Zn (4) is prevented by means of a floating preventing member (5). The molten Zn (4) is heated while covering the liquid surface thereof with a carbonaceous material (9) to melt the metal Si powder (6) in the molten Zn (4). The prevention of the floating of the metal Si powder (6) is terminated, and a molten Zn-Si alloy (11) which is produced by dispersing the molten Si in the molten Zn (4) is filled in a copper-made casting mold (12) and is then rapidly cooled, thereby producing a billet.