An image forming apparatus includes a photosensitive member being movable
in a predetermined direction; a charging roller that charges a surface of
the photosensitive member; and a static pre-eliminator that eliminates
static electricity by irradiating the surface of the photosensitive
member with light, the static pre-eliminator located on an upstream side
of the charging roller in a direction of movement of the photosensitive
member; wherein an arrangement and an exposure amount of the static
pre-eliminator are set to satisfy E .ltoreq.0.025.times.exp(t/.tau.)
where .tau.is a residual time constant of a photo carrier generated in
the photosensitive member by the static pre-eliminator, t is a time
period from a time when the photosensitive member passes through the
static pre-eliminator to a time when the photosensitive member is charged
by the charging roller, and E is a normalized exposure amount of the
static pre-eliminator.