The invention provides a manufacturing method and a manufacturing apparatus for an electrical device with film covering. The manufacturing method for the electrical device with film covering according to the invention can be employed to realize the effect that electrolyte is hard to be uneven in permeation in a battery set so that the electrolyte can be filled within a short time period. The manufacturing method for the electrical device with film covering comprises a pressure reducing procedure for reducing the pressure inside an electrolyte filling cavity equipped with a bag-shaped laminated film package body to lower than the atmospheric pressure, wherein the bag-shaped laminated film package body is provided with an opening part and accommodates the battery set, and the battery set is provided with an anode and a cathode which are laminated up and separated by an insulating film; an electrolyte filling procedure for filling the electrolyte of a specified amount from the opening part into the package body, after the pressuring reducing procedure; and a pressuring increasing and reducing procedure for increasing the pressure inside the electrolyte filling cavity to higher than the pressure in the electrolyte filling procedure and then reducing the pressure, after the electrolyte filling procedure and before sealing the opening part.