Abstract: A magnesium battery (10) is constituted of a negative electrode (1), a positive electrode (2) and an electrolyte (3). The negative electrode (1) is formed of metallic magnesium and can also be formed of an alloy. The positive electrode (2) is composed of a positive electrode active material, for example, a metal oxide, graphite fluoride ((CF)n) or the like, etc. The electrolytic solution (3) is, for example, a magnesium ion-containing nonaqueous electrolytic solution prepared by dissolving magnesium(II) chloride (MgCl2) and dimethylaluminum chloride ((CH3)2AlCl) in tetrahydrofuran (THF). In the case of dissolving and depositing magnesium by using this electrolytic solution, the following reaction proceeds in the normal direction or reverse direction.