A cleaning device is provided with a cleaning unit (35) disposed downstream from a position at which a toner image is transferred to a paper. The cleaning unit (35) is provided with a cleaning blade (35c) for scraping off residual toner attached to an image bearing member and a toner catching sheet (35e) for preventing the residual toner or paper dust which have been scraped off from falling outside the cleaning unit. The free length in the toner catching sheet (35e) between affixed positions of a first end portion which is affixed to the cleaning unit (35) and a second end portion which abuts an outer circumferential portion of the image bearing member is determined by an amount of paper dust buildup on the outer circumferential portion of the image bearing member.