A rechargeable battery exchanging method which exchanges rechargeable batteries of an assembled battery to rebuild new assembled battery. The method includes discharging a rechargeable battery derived from an assembled battery until the rechargeable battery becomes a fully discharged state and storing the rechargeable battery in a storage region for a predetermined period of time or longer from when the rechargeable battery becomes the fully discharged state to prepare a reusable rechargeable battery. The method further includes rebuilding a regenerated assembled battery by combining the stored reusable rechargeable battery with a stored reusable rechargeable battery derived from other assembled batteries or combining the stored reusable rechargeable battery with a fresh rechargeable battery.