A manufacturing method for an aluminum film, in which aluminum is electrodeposited on a surface of a long, porous resin substrate imparted with electrical conductivity in a molten salt electrolytic solution, comprising: a step of transferring the substrate into a plating chamber through a sealing chamber disposed on the entrance side of the plating chamber; a step of electrodepositing an aluminum film on the surface of the substrate in the plating chamber; and a step of transferring the substrate having the aluminum film electrodeposited thereon from the plating chamber through a sealing chamber disposed on the exit side of the plating chamber; wherein: an inert gas is supplied into the plating chamber such that the plating chamber has a positive pressure relative to outside air, the inert gas is forcibly discharged from an inert gas exhaust provided on each of the two sealing chambers (4,5); the inert gas exhaust pipe is provided at the substrate entrance side in the sealing chamber disposed on the entrance side, the inert gas exhaust pipe is provided at the substrate exit side in the sealing chamber disposed on the exit side, an inert gas supply pipe that supplies an inert gas is further provided on each of the two sealing chambers (4,5), the inert gas supply pipe is provided at the substrate exit side in the sealing chamber disposed on the entrance side, and the inert gas supply pipe is provided at the substrate entrance side in the sealing chamber disposed on the exit side, characterised in that the inert gas supplied by each inert gas supply pipe is blown to the substrate in an inclined manner with respect to the substrate so that an inert gas stream moving from the plating chamber side toward the inert gas exhaust pipe is formed. a step of transferring the substrate into a plating chamber through a sealing chamber disposed on the entrance side of the plating chamber; a step of electrodepositing an aluminum film on the surface of the substrate in the plating chamber; and a step of transferring the substrate having the aluminum film electrodeposited thereon from the plating chamber through a sealing chamber disposed on the exit side of the plating chamber; wherein: an inert gas is supplied into the plating chamber such that the plating chamber has a positive pressure relative to outside air, the inert gas is forcibly discharged from an inert gas exhaust provided on each of the two sealing chambers (4,5); the inert gas exhaust pipe is provided at the substrate entrance side in the sealing chamber disposed on the entrance side, the inert gas exhaust pipe is provided at the substrate exit side in the sealing chamber disposed on the exit side, an inert gas supply pipe that supplies an inert gas is further provided on each of the two sealing chambers (4,5), the inert gas supply pipe is provided at the substrate exit side in the sealing chamber disposed on the entrance side, and the inert gas supply pipe is provided at the substrate entrance side in the sealing chamber disposed on the exit side, characterised in that the inert gas supplied by each inert gas supply pipe is blown to the substrate in an inclined manner with respect to the substrate so that an inert gas stream moving from the plating chamber side toward the inert gas exhaust pipe is formed. an inert gas is supplied into the plating chamber such that the plating chamber has a positive pressure relative to outside air, the inert gas is forcibly discharged from an inert gas exhaust provided on each of the two sealing chambers (4,5); the inert gas exhaust pipe is provided at the substrate entrance side in the sealing chamber disposed on the entrance side, the inert gas exhaust pipe is provided at the substrate exit side in the sealing chamber disposed on the exit side, an inert gas supply pipe that supplies an inert gas is further provided on each of the two sealing chambers (4,5), the inert gas supply pipe is provided at the substrate exit side in the sealing chamber disposed on the entrance side, and the inert gas supply pipe is provided at the substrate entrance side in the sealing chamber disposed on the exit side, characterised in that the inert gas supplied by each inert gas supply pipe is blown to the substrate in an inclined manner with respect to the substrate so that an inert gas stream moving from the plating chamber side toward the inert gas exhaust pipe is formed.