The invention relates to a toner, a development agent, a toner container, and an image forming apparatus for electrophotography. Provided is a toner that is endurable to an external force, does not disengage with, move or bury an external additive, has excellent heat preservation and fixation performance, can inhibit changes in characteristics such as charge amount, mobility, agglutination degree and inhibit image quality degradation, a development agent using the toner, a development agent container, and an image forming apparatus. The toner is composed of a mother toner particle containing a binder resin and a coloring agent, and an external additive to cover the mother toner particle, wherein the external additive contains a resin particle which has an outer shell layer formed of silica or modified silica; the resin particle has a non-spherical form with a shape factor (SF) of 1.20 or greater as calculated by the following formula (I): Shape factor(SF)=[(Absolute maximum length of particle)2 / Projected area of particle)]([pi] / 4).