An image forming apparatus has a developing device and a controller. The developing device includes a stirring member, rotatable at a first speed or at a second speed lower than the first speed, which varies, according to its speed, the amount of developer discharged out of the developing device. The controller drives the stirring member to rotate at the second speed, then switches the rotation speed of the stirring member to a third speed higher than the second speed but lower than the first speed, and then drives the stirring member to rotate at the third speed for a first period. The third speed is set higher the lower the fluidity of the developer.