Disclosed is a method of manufacturing a secondary battery wherein an electrode assembly impregnated with an electrolytic solution is embedded in a battery case, wherein interfacial contact properties (i.e. wetting) of the electrode assembly and the electrolytic solution are improved through a process including: (a) impregnating an electrode assembly having a separator interposed between a cathode and an anode with an electrolytic solution; and (b) applying vibration having a frequency of 20 to 100 kHz to an electrolytic solution with which the electrode assembly is impregnated. A secondary battery manufactured according to the method may have improved ionic conductivity, electronic conductivity and the like and, as such, may have improved electrochemical performance.