An image forming apparatus includes an image bearing member, a charging device which charges the image bearing member, an exposure device which exposes the charged image bearing member to light, a developing device having a developer carrying member, and developing the electrostatic latent image by supplying the developer from the developer carrying member, and an instructing portion which generates an instruction signal for instructing to perform a developer install mode for installing developer in the developing device at a time of non-image formation. In the developer install mode a control portion sets an absolute value of a potential on the image bearing member charged by the charging device to a value which is smaller than an absolute value of a potential of the developer carrying member caused by a direct current component of the bias to be applied to the developing device and larger than an absolute value of an image dark section potential on the image bearing member at the time of image formation.