According to one aspect of the invention, a remanufacturing method of a liquid container forms an inlet in a downstream wall surface of a second chamber, which defines part of a bottom face of the liquid container. In the state of closing a liquid feeder and opening an air open structure, the remanufacturing method injects a liquid through the inlet to fill the second chamber with the liquid. In the state of opening the liquid feeder and closing the air open structure, the remanufacturing method injects the liquid through the inlet to fill a space from the second chamber to the liquid feeder with the liquid. The remanufacturing process seals the inlet after completion of the injection of the liquid. This arrangement enables the liquid to be efficiently refilled into the liquid container without damaging the functions of the liquid container.