Developing device and image forming apparatus

A developing device that supplies toner to and develops an electrostatic image formed on a latent-image carrier, the developing device comprising:

• a housing;
• a rotating shaft;
• a rotator that rotates with the rotating shaft;
• and
• a bearing element that supports the rotating shaft to the housing,
• the bearing element formed of a composite material, the composite material containing thermoplastic olefin resin as a base material and a lubricity enhancing material, the composite material having at least a ratio of numerical values of Rockwell hardness (based on R scale of JIS K7202)/bending elastic modulus in GPa (based on JIS K7171) in a range from 25 to 45, and the composite material having a frictional coefficient that is lower than that of the base material.