A development unit comprising a case (230), which accommodates toner therein, a developing roller (211), rotatably supported by the case through a first shaft (212) and 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, characterised in that the elastic member is comprised of an expanded material having an open cell ratio of 30% or more, an engagement depth of the supply roller with respect to the developing roller is 0.4mm or less, and the toner has a shape factor SF-1 of 150 or less, and a shape factor SF-2 of 140 or less.