Provided is a molten salt battery whose cycle life is improved by using an electrolyte that is unlikely to cause corrosion of aluminum. In the molten salt battery of the present invention, the total concentration of iron ions and nickel ions contained as impurities in the electrolyte composed of a molten salt is set to be 0.1% by weight or less, preferably 0.01% by weight or less. Because of the low total concentration of iron ions and nickel ions contained in the electrolyte, corrosion of the electrode current collector composed of aluminum is inhibited, and the cycle life of the molten salt battery is improved.