An image forming apparatus includes a photosensitive drum, a charging roller,
a transfer roller, and a toner charging brush, wherein the toner charging brush
reciprocates in a longitudinal direction of the photosensitive drum. In the image
forming apparatus, when a number of rotations per a unit time of the image bearing
member is assumed to be "a" and a number of times of reciprocation per unit time
of the toner charging brush is assumed to be "b", assuming that R=b/a, R is set
to be in a range of 1/25R3. However, R=m/n (m and n are integers
of 5 or less) is excluded. Consequently, generation of a periodic attachment pattern
appearing on the photosensitive drum is eliminated.
