The present invention relates a toner cartridge used for a laser printer. The toner cartridge comprises: a toner tank for storing fresh toner and a waste toner tank for storing waste toner obtained after development. When the toner cartridge is installed in a laser printer, the toner tank has a toner supplying section at a lower portion in a vertical direction thereof for supplying toner to an external environment. Two inner surfaces of the toner tank, arranged in a transverse direction of the toner tank and parallel with a direction in which the toner cartridge is installed into the laser printer, keep in a plane state at positions higher than the toner supplying section and are parallel with the vertical direction.