An image forming apparatus is provided with a latent image forming member for forming first and second electrostatic latent images on an image bearing member. A first developer forms a first visualized image by developing the first electrostatic latent image, and a second developer provides a second visualized image by developing the second electrostatic latent image. The second developer acts on the image bearing member after the first visualized image is formed on the image bearing member, and the second developer includes a developer carrier for carrying a developer to a developing position where the developer is supplied to the image bearing member. A vibratory voltage is applied to the developer carrier of the second developer. A controller changes a duty ratio of the vibratory voltage. The vibratory voltage has a first peak for forming an electric field to urge the developer away from the developing carrier toward the image bearing member and a second peak for forming an electric field to urge the developer away from the image bearing member toward the developer carrier. The first peak and second peak are alternately applied, and the controller changes a duty ratio while maintaining the second peak substantially constant. Furthermore, the controller changes the duty ratio by changing the first peak.