A waste-toner collecting device includes a cleaning unit that collects waste toner remaining on an image carrier; a conveying belt that conveys the waste toner collected by the cleaning unit in a first direction; and a conveying screw that conveys the waste toner conveyed by the conveying belt in a second direction. An end of the conveying screw on a side of the conveying belt is rotatably supported by an inner wall of a body of the waste-toner collecting device in a state where the end of the conveying screw is in contact with the inner wall.