An image forming apparatus is provided. The image forming apparatus includes a photosensitive member, a developing roller which carries developer and contacts the photosensitive member, and a control device which is configured to apply, to the developing roller, a developing bias having a direct current component and an alternating current component overlapped with each other so as to supply developer from the developing roller to the photosensitive member. The control device is configured to execute either one of a first mode in which an amplitude of the alternating current component of the developing bias is set with a first set value and a second mode in which the amplitude of the alternating current component of the developing bias is set with a second set value larger than the first set value, based on whether or not a temperature of the developing roller is a first predetermined value or larger.