Photosensitive drum and vibration reduction method for same, and photosensitive drum unit

A method for reducing vibrations of a photosensitive drum comprising a tube-shaped conductive base having a surface on which a photosensitive layer is formed, and a flange attached to an end of the conductive base, wherein the method comprises:

• inserting the flange from the end of the conductive base, and
• bringing the flange into contact with an inner surface of the conductive base within an electrically-charged region of the conductive base to thereby reduce a forced vibration of the conductive base resulting from an exciting force associated with electrical charging, wherein the flange is brought into contact with the inner surface of the conductive base within the contact region between the photosensitive layer formed on the surface of the conductive base and an electrifier for electrically charging the photosensitive layer.