A developing device includes an image carrier on which an electrostatic latent image is formed, a developing member facing the image carrier to supply a developing agent to the electrostatic latent image formed on the image carrier, a rotary member facing the outer circumference of the image carrier in a non-contact state to collect toner scattered from the developing member, and a gear train to drive the rotary member. An effect that the developing member is subjected to by the driving of the rotary member is minimized, thereby preventing deterioration of image quality. Also, the scattering of the developing agent is effectively prevented by adjusting the drive rotational velocity of the rotary member.