Disclosed is a method of manufacturing a secondary battery, built in a battery case, having an electrode assembly impregnated with an electrolyte solution, the method including: (a) injecting an electrolyte solution as a target into a chamber equipped with a vibrating probe; (b) impregnating by soaking an electrode assembly, which has a separator interposed between a cathode and an anode, in an electrolyte solution contained in the chamber; (c) applying vibration at a frequency of 20 to 100 kHz of to the electrolyte solution with the vibrating probe; and (d) moving the electrode assembly with the electrolyte solution into a battery case, whereby interfacial wetting of the electrode assembly and the electrolyte solution is improved. A secondary battery manufactured according to the method may have improved electrolyte solution impregnation properties, ionic conductivity, electronic conductivity and the like and, as such, may have improved electrochemical performance.