A developing unit to supply toner to a photosensitive medium of an image forming apparatus to form an image thereon, including a housing to hold a toner of a predetermined color, a developing roller which is coupled to the housing to be rotatable in a direction opposite to a moving direction of the photosensitive medium, to supply the photosensitive medium with the toner, and to form the image by potential difference, and a regulating blade including a coupling end part coupled to the housing and a free end part double bent with regard to the coupling end part to contact the developing roller at a tip part thereof.