In initial charge and discharge, decomposition products or a gas is generated, degrading a battery. At least one of solvents (e.g., ethylene carbonate) used for an electrolytic solution is brought into contact with a positive electrode and a negative electrode and then charge is performed to some degree, and after that, a different solvent or electrolytic solution (e.g., ethyl methyl carbonate or vinylene carbonate) was added to adjust the electrolytic solution and then charge is performed. Through this process, stable coating films are formed in initial charge and discharge, which stably inhibits a side reaction between the electrolytic solution and an active material.