A developing device (50) includes a developing sleeve (53) for supplying
toner particles (T) to a latent image area (22) on a peripheral surface
of a photoconductive drum (20) while rotating about a central shaft
(534). The developing sleeve (53) has an immovable sleeve magnet (533)
therein. Two magnetic members (82) are disposed in opposite end portions
of the developing sleeve (53) and are spaced a predetermined distance
from the peripheral surface of the developing sleeve. Each magnet member
(82) has an arc shape. A magnetic member magnet (83) is mounted in the
magnet member (82) and faces a sleeve magnet (533) so that opposite
facing portions of the magnetic member magnet (83) and the sleeve magnet
(533) have the same polarity. With this construction, toner particles are
prevented from leaking from the end portions of the developing sleeve
(53).