It is an object of the present invention to provide a method for producing a secondary battery in which water in the outer package can be removed even when the secondary battery includes an electrolytic solution containing a halogen-containing compound. The present exemplary embodiment is a method for producing a secondary battery including an electrolytic solution containing a supporting salt, a nonaqueous solvent, and a halogen-containing compound, an electrode assembly including a negative electrode and a positive electrode, and an outer package, the method including (1) disposing a first solution containing at least the supporting salt and the nonaqueous solvent, and the electrode assembly in the outer package; (2) charging the electrode assembly; (3) emitting from the outer package a gas generated by the charge; and (4) injecting a second solution including at least the halogen-containing compound into the outer package after the gas is emitted, wherein the first solution does not contain the halogen-containing compound, and the electrolytic solution includes the first solution and the second solution.