An electrostatic coating method in which a coating material cartridge is used. When a coating material feeding path (68, 88) is cleaned by a liquid fed from a coating material feeding unit (20), the liquid is fed from the coating material feeding unit to a storage part (13) and stored. The liquid in the storage part is then fed to a fluid chamber (83) inside a coating material cartridge (19) via a fluid circuit (10A). The liquid in the fluid chamber pushes out the electrically conductive coating material inside a coating material chamber (84) via a free piston (82), and the electrically conductive coating material is fed to a coating gun (14).