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 in 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≦0.025×exp(t/τ) where τ 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.