US Patent 7526217 Image forming apparatus and waste toner warning method

An image forming apparatus for executing image forming process on a page by page basis including: a toner image forming section for producing a visible image formed of toner as a toner image on an image carrier; a transfer section which performs a transfer process for transferring the formed toner image onto a recording medium; a cleaning section which removes toner remaining on the image carrier after the transfer process; a waste toner storing section in which the removed toner is accumulated; and a waste toner amount detecting section which detects an amount of the toner accumulated in the waste toner storing section on the basis of at least three detection levels.