An electric charging apparatus (5) has a charge mechanism for charging a power supply device inside plural power supply assemblies (30) respectively attached to plural pieces of traveling equipment (10). Furthermore, the electric charging apparatus (5) has an electric power source assembly swapping mechanism (200). The electric power source assembly swapping mechanism (200) dismounts the first electric power source assembly (30) from the traveling equipment (10) and moves it to the charge mechanism, and moves it to mount the second electric power source assembly (30) on traveling equipment from charge mechanism. In addition, the electric power source assembly swapping mechanism (200) dismounts the second electric power source assembly (30) from traveling equipment (10) and moves it to the charge mechanism, and moves it to mount the first electric power source assembly (30) on traveling equipment (10) from charge mechanism.