A method of manufacturing a lithium-ion secondary battery includes an electrolytic solution making step of making an electrolytic solution by mixing at least an organic solvent and an electrolytic salt together, an electrode insertion step of inserting an anode and a cathode into an outer case, and a liquid injection step of injecting the electrolytic solution into the outer case; wherein the electrolytic solution making step or the liquid injection step adds a compound having an alkyl group with a carbon number of 10 or greater and an epoxy, vinyl, or silanol group at a terminal to the electrolytic solution.