An image forming apparatus comprises latent image forming means for forming a latent image on a photosensitive medium, reference latent image forming means for forming a reference latent image adjacent to the latent image, a plurality of light-emitting means disposed at intervals of a pitch D equal to or smaller than the width l of the reference latent image, and means for drivingly controlling the plurality of light-emitting means in accordance with the size of the latent image.