In an electron-emitting device having an electron-emitting member
containing carbon as a main component, and an extraction electrode
arranged near the electron-emitting member, electrons can be emitted by
substantially only a region of the electron-emitting member close to the
extraction electrode. Brightness nonuniformity and abnormal lights-on
errors are reduced in an image forming apparatus in which the
electron-emitting devices are constituted into an electron. The
electron-emitting threshold field of the electron-emitting member is set
low at a portion close to the extraction electrode and high at a portion
apart from the extraction electrode.