To provide a developing apparatus where conditions such as the rotating velocity of a belt member and a developer quantity on the belt member are optimized in order to appropriately set the quantity of developer to be carried to an image carrier.

In the developing apparatus where an electrostatic latent image on a photoreceptor drum 1 is developed by scattering the developer carried by the belt member 101 toward the photoreceptor drum 1 by a traveling wave electric field, provided that the processing velocity of the photoreceptor drum 1 is expressed by vp, a toner quantity necessary on the photoreceptor drum 1 is expressed by mp, the rotating velocity of the belt member 101 is expressed by vb, and the developer quantity on the belt member 101 is expressed by mb, the following inequality (1) is satisfied; the inequality (1) is shown by vp×mp<vb×mb<1.93×vp×mp.