An image forming apparatus includes a plurality of developing devices each including a developer carrying member for carrying a developer to develop an electrostatic latent image formed on an image bearing member, and a developer regulating member for regulating the developer carried on the developer carrying member; a common voltage applying device for applying a common voltage to the plurality of the developer regulating member. When a first one of the developer carrying members is rotating, and when a second one of the developer carrying members is not rotating, a potential difference between a potential of the second developer carrying member and the common voltage is smaller than a potential difference between a potential of the first developer carrying member and the common voltage.