An optical writing device stores pieces of dithering information indicating dithering patterns whose densities are different, each piece of dithering information including pieces of identification information associated with pixels of the corresponding dithering pattern, and stores pieces of pixel setting information in which pieces of colored/colorless information indicating each of the pixels is colored or colorless are associated with the pieces of identification information, the pieces of colored/colorless information being set based on a resolution of a light source for forming an electrostatic latent image. The optical writing device also includes a control unit configured to arrange the same dithering patterns in a way that the dithering patterns form a pattern with a given size, and cause the light source to emit light based on information generated by setting the pixels of each of the same dithering patterns to be colored or colorless in accordance with the pixel setting information.