1. An image forming apparatus which includes image forming means for forming a latent image on a photoconductor using a developer of a single color or a plurality of colors, thus forming an image, the apparatus comprising: an environment detection section that detects an environment of the developer including a temperature and a relative humidity, the environment detection section being provided near a developing section that supplies the developer of the single color or the plurality of colors; a computing section that computes an environment parameter value on the basis of an environment condition detected by the environment detection section; a determination section that determines a development contrast potential for each of the colors of the developer, using the environment parameter value computed by the computing section; and a control section that controls the image forming means so as to obtain the development contrast potential determined by the determination section.