A developing device prevents deterioration of toner, i.e., prevent the toner from being damaged, or fused onto the blade, to realize a more reliable developing operation. In the developing device, an electron emitting section is provided onto the toner regulation blade in which apertures (151) are formed, wherein each of the apertures (151) is formed by electroforming to have an inner surface curved convexly to be widened outwardly to the side irradiated with an ultraviolet ray (shape A). Further, a photoelectric surface (152) is laminated on the surface of the electron emitting section with the apertures (151). With an application of ultraviolet ray onto the electron emitting section, the resulting photoelectrons as emitted from the photoelectric surface (152) are guided to the toner through the apertures (151). Here, for the aperture (151) of the shape A, a larger amount of electrons can be guided to the toner than the apertures in other shapes (B to E).