The film formation method comprises the steps of: unrolling and feeding an elongated substrate wound in a roll form from a first roll chamber in a first direction from the first roll chamber toward a second roll chamber; degassing the fed substrate; forming a first material film on a first surface in a first film formation chamber; guiding the substrate having the first material film formed thereon to a second film formation chamber in a second direction from the second roll chamber toward the first roll chamber; forming, in the second film formation chamber, a second material film on a second surface opposite the first surface of the substrate when it is being guided in the second direction; taking up, in a third roll chamber provided between the first roll chamber and the second roll chamber, the substrate in a roll state.