Image forming apparatus having developer amount detector

An image forming apparatus, which forms an image using a cartridge having a memory, said image forming apparatus comprising:

• a developer container configured to contain developer;
• a developer amount detecting portion configured to detect the remaining amount of the developer contained in said developer container,
• wherein the memory stores first information indicating that the remaining amount of the developer detected by said developer amount detecting portion is a first predetermined value or less, and second information indicating that the remaining amount of the developer detected by said developer amount detecting portion is a second predetermined value or less, the second predetermined value being less than the first predetermined value;
• and
• a controller, which writes the first information in the memory when the remaining amount of the developer detected by said developer amount detecting portion is the first predetermined value or less, and which writes the second information in the memory when the remaining amount of the developer detected by said developer amount detecting portion is the second predetermined value or less,
• wherein said controller outputs a signal indicating an abnormality in said image forming apparatus or the cartridge in the case in which the first information is not written in the memory and in which the second information is written in the memory.