A developing device that is mounted to an electrophotographic image forming
apparatus main body to be used for developing an electrostatic latent
image formed on an electrophotographic photosensitive member, which
includes a developing sleeve for developing the electrostatic latent image
formed on the electrophotographic photosensitive member, a first
electrode; a second electrode opposed to the first electrode, and an
electrical contact portion for receiving a bias applied to the developing
sleeve and the second electrode from the electrophotographic image forming
apparatus main body, and in which the first electrode and the second
electrode are arranged in positions to which a developer can be admitted,
and a value corresponding to a capacitance between the first electrode and
the second electrode which exists at the time of applying a voltage to the
second electrode is detected by the electrophotographic image forming
apparatus main body, thereby detecting a developer amount by the
electrophotographic image forming apparatus main body.
