An image forming apparatus, which comprises a toner density detection device for detecting the density of a toner inside a developing device, acquires the number of pixels from inputted image information, calculates the toner replenishment amount from the toner density detection value and the information on the pixels, and thereby performs replenishment control so that excessive replenishment or insufficient replenishment of the toner is not caused. The upper limit value of the amount of toner to be replenished at once to the developing device is changed in accordance with the amount of information on an input image such as the image area, pixels of the input image.