Molten chlorides such as potassium chloride, sodium chloride and aluminium chloride are used as fluxes for the purification treatment of scrap aluminium. In order to clarify the reactivity of aluminium alloy melts with these molten salts, the dissolution behaviors of Al-4.7wt%Mg and Al-6.04wt%Zn alloys in KCl-NaCl binary melt and KCl-NaCl-AlCl₃ ternary melt have been investigated by the equilibrium experiment conducted with various temperatures and compositions of molten salt. The dissolution reaction of magnesium in KCl-NaCl binary melt greatly proceeded with an increase in temperature, but at high temperatures, this reaction was retained with raising temperature. The changes of these dissolution behaviors may be attributed to the dissolution of aluminium in alloy, which was remarkably accelerated at temeperatures above 760°C. The dissolution reaction of zinc in KCl-NaCl-AlCl₃ ternary melt increased with increases in temperture and content of aluminium chloride. In this system, aluminium in alloy dissolves significantly by the disproportionation reaction even in molten salt of low aluminium chloride concentration. Distribution coefficient of magnesium was enlarged with increasing temperature, and at high temperatures, it showed a maximum value at a given temperature depending on the content of sodium chloride in KCl-NaCl binary melt. Distribution coefficient of zinc was enlarged as the temperature and the content of aluminium chloride in KCl-NaCl-AlCl₃ ternary melt increased.