A representative configuration of an image forming apparatus has a plurality of developing devices, each of which develops an electrostatic latent image formed on a photosensitive drum into a toner image using developer of plural colors. The image forming apparatus includes a density sensor which detects the amount of toner of the toner image for each color. In a case where it is determined that the amount of toner of any color departs from a predetermined range based on the detection result of the density sensor, development conditions of the rest of the developing devices, other than the developing device departing from the predetermined range, are changed such that the image densities developed by the respective developing devices are equal to each other.