A developing device includes a rotatable toner bearing roller and a regulation blade. The toner bearing roller has regularly-arranged projecting sections and non-projecting sections, bears toner whose volume average particle diameter is smaller than a depth of the non-projecting section relative to the projecting section, and develops a latent image borne on an image bearing member with the toner borne on the toner bearing roller. The regulation blade is for regulating an amount of the toner borne on the toner bearing roller, and abuts, with a predetermined width, against a circumferential surface of the toner bearing roller in a circumferential direction thereof in such a manner that a longitudinal direction of the regulation blade is along a direction of a rotation axis of the toner bearing roller. A tip edge of the regulation blade in a lateral direction and a thickness direction thereof is located within an abutting section having the predetermined width. The predetermined width is larger than a maximum width, in the circumferential direction, of the non-projecting section.