Developing unit

摘要

A developing unit comprising a case (230), which accommodates therein toner containing pigment by 5 wt% or more; a developing roller (211), rotatably supported by the case through a first shaft (212); a supply roller (240), rotatably supported by the case through a second shaft (241), the supply roller being formed by an elastic member arranged to be pressed against the developing roller in such a manner as to supply the toner to the surface of the developing roller; and a restraining blade (260), which restrains a quantity of toner on the developing roller, characterised in that a covering ratio of a first additive with respect to matrix particle surfaces of the toner is 100% or more. <IMAGE>