A developing device and an image forming apparatus which can form a printing image having high resolution and a high quality level, while resolving various problems resulted from the use of small particle size toner particles are provided. The developing device includes a toner constituted of resin base particles containing a coloring agent and a binder resin, and silicone oil and/or fluoro oil added to the resin base particles, a toner receiving portion for receiving the toner, and a developing roller having an outer peripheral surface and an irregularity section for carrying the toner, the irregularity section formed on the outer peripheral surface and including a plurality of depression portions and/or protrusion portions provided regularly and uniformly, wherein an average particle size of the resin base particles in volume basis is in the range of 2 to 4 μm, and an added amount of the silicone oil and/or fluoro oil to the resin base particles is in the range of 0.05 to 2 mass %.