For a cleaning the conveyor belt of the image forming apparatus, the adhesive surface of the sheet of the sheet roller abuts on the outer surface of the conveyor belt, and the conveyor belt is driven in a direction so that the sheet roller rotates to roll the sheet in order to conduct a cleaning. For a renewal of the sheet, the conveyor belt is driven in a direction so that the sheet roller to unroll the sheet, the sheet is unrolled for a predetermined length, adhered to the outer surface of the conveyor belt and cut off in order to renew the adhesive surface of the sheet of the sheet roller.