A developing device includes a developing roller including a base and a surface layer formed on the base, the surface layer including a polyurethane resin having a fluorine group and a polyfunctional isocyanurate structure, a toner storage chamber being partially in contact with the developing roller and to support the developing roller, and a sealing member provided at opposed ends of an end portion of the toner storage chamber in a rotating axis direction of the developing roller, and to seal in toner moving to the end portion of the toner storage chamber, the sealing member before use having a coefficient of static friction in a range of from 0.08 to 0.19.