An image forming apparatus includes an image bearing member, a developing device, a toner content detecting portion, a toner supplying device, an image ratio calculating portion, a toner image density detecting portion, an adjusting portion, and a controller. The controller is configured to control an execution frequency of the adjusting portion so that execution by the adjusting portion is carried out after a number of times of image formation after occurrence of a change rate of the image ratio that is greater than a predetermined change rate reaches a first value, and execution by the adjusting portion is carried out after the number of times of image formation after occurrence of a change rate of the image ratio that is less than the predetermined change rate reaches a second value greater than the first value.