PURPOSE: To obtain a color image with good color reproducibility by providing a coating control means which has one end opposite one magnetic pole of a magnetic field generating means and the other end positioned at the downstream side of a toner carrier in its moving direction opposite a magnetic pole opposite in polarity.

CONSTITUTION: A magnetic blade 15 is formed in a U shape; and one end 15a of the blade 15 is arranged opposite the magetic pole 14(S3) at the upstream side in the rotating direction of a sleeve 8 and the other end 15b of the blade at the downstream side is arranged opposite the magnetic pole 16(N4) opposite in polarity of the magnetic pole 14. Therefore, the tips 15a and 15b and magnetic poles 14 and 16 form a magnetic circuit to increase the magnetic force at a coating part. Consequently, a toner coat layer which is thin and uniform is obtained to form an image which has no density irregularity and suits to a color high in brightness and saturation.