Provided is a sodium molten-salt battery having good charge-discharge cycle characteristics. The sodium molten-salt battery includes a positive electrode that contains a positive electrode active material, a negative electrode that contains a negative electrode active material, and a molten-salt electrolyte that contains a sodium salt and an ionic liquid that dissolves the sodium salt. The negative electrode active material contains non-graphitizable carbon. The ionic liquid is a salt of a bis(sulfonyl)imide anion and a first onium cation that does not cause a Faradaic reaction with the non-graphitizable carbon. The molten-salt electrolyte contains a second onium cation in an amount of 1,000 ppm by mass or less. The second onium cation is represented by a general formula (1): R1R2R3R4N+ where R1 to R4 are each independently a hydrogen atom or a methyl group.