NOVELTY - A battery element chosen from a positive electrode, a negative electrode and a separator is prepared. A solution containing electrolyte and a solvent which dissolves the electrolyte, is prepared. The battery element holds solution. The solvent is removed from battery element holding solution. An electrode group (11), which comprises a positive electrode, a negative electrode and a separator, is formed after removing the solvent. The electrode group is accommodated in the battery case (10), to obtain the molten salt battery (100).    USE - Manufacture of molten salt battery (claimed). Uses include but are not limited to power supply for electric power storage, batteries for electric vehicles, and night time electric power storage.    ADVANTAGE - The molten salt battery having excellent productivity and charging/discharging cycling characteristics is manufactured by simple process.    DETAILED DESCRIPTION - A battery element chosen from a positive electrode, a negative electrode and a separator is prepared. A solution containing an electrolyte, which is in solid state at room temperature and has sodium ion conductivity when melted, and a solvent which dissolves the electrolyte, is prepared. The battery element holds the solution. The solvent is removed from the battery element holding the solution. An electrode group, which comprises a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, is formed after removing the solvent from the battery element. The electrode group is accommodated in the battery case, to obtain the molten salt battery. An INDEPENDENT CLAIM is included for manufacturing apparatus of molten salt battery element, which contains solution storage portion for accommodating the solution containing electrolyte and solvent, solution supply apparatus for holding solution to battery element, and removal apparatus for removing solvent from battery element.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of battery case of molten salt battery.    Positive electrode lead piece (2a)    Battery case (10)    Electrode group (11)    Positive electrode terminal (14)    Molten salt battery (100)