The present invention relates to a toner cartridge, which contains the toner directly in a housing. The housing has an opening. A plug is disposed in the housing where the opening is. The plug has a small diameter portion that has a diameter smaller than the opening. A piston is disposed in the housing to be biased by an elastic member to the plug for sealing the opening. Such toner cartridge has a simple structure to reduce the cost of fabrication and use and has a function of preventing leaking toner.