A developer cartridge is provided, which includes a toner cartridge, a developer stirring device located in the toner cartridge, a supply roller for supplying a developer to a developer roller, a developer roller for developing an electrostatic latent image on a photoconductor, and a power receptor for driving only one of gear sets of the above means to receive a power. The power receptor is rotatably fixed at two or more predetermined positions. An initial position of the power receptor is a power receiving position. A power receptor moving device includes a press block, a baffle block, a spring, and a torsion spring. The power receptor moving device is controlled by the press block. When the press block of the power receptor moving device is pressed downwards, the power receptor is rotated to another power receiving position due to the action of the torsion spring. The present invention is applicable to various types of machines.