1. An image forming apparatus comprising: an image carrier having an image carrying surface for forming an electric latent image thereon; a developer carrier being disposed facing to the image carrying surface, and having a developer carrying surface for carrying a developer for developing the electrostatic latent image formed on the image carrying surface; an electric field generating unit for generating the development field between the image carrying surface and the developer carrying surface, the development field developing the electrostatic latent image; a space detecting unit for detecting a space between the image carrying surface and the developer carrying surface; a correcting unit for correcting the intensity of the development field based on the space detected by the space detecting unit and the correspondence relation between the image density of a visible image transferred from the image carrying surface to a transferred medium and the intensity of the development field for suppressing the density unevenness of the visible image; wherein, when the visible image corresponding to the electrostatic latent image includes both a low density range in which the density unevenness of the visible image appears remarkably and a density range higher than the low density range, an instruction receiving unit receives an instruction from a user to the correcting unit to correct the intensity of the development field corresponding to the low image density range or the high density range.