A latent image forming unit forms an electrostatic latent image corresponding to an image signal on an image carrier. A development unit includes a circulation mechanism for causing developer within a development unit to circulate, and develops the electrostatic latent image using the developer. A detector unit detects a toner density of the developer within the development unit. A determination unit determines a replenishment amount of toner to the development unit based on the toner density detected by the detector unit. A replenisher unit replenishes the development unit with toner in accordance with the replenishment amount. The control unit reduces a ripple that occurs in accordance with a period of circulation of the developer, by executing filter processing for reducing the ripple.