The image forming apparatus includes a developing device, a movable member, a replenishment device, a developer replenishment path, and a conveyance screw so arranged within the developer replenishment path as not to come into contact with the internal wall of the developer replenishment path, wherein X (g) representing the quantity of the developer for replenishment present in the clearance section between the developer replenishment path and the conveyance screw, Y (g) representing the quantity of the developer in the developing device, Q(.mu.C/mg) representing the absolute value of the electric charge per unit weight of the toner in the developing device, and A(.mu.C/mg) representing the absolute value of the electric charge per unit weight of the toner relative to a 1% variation in the toner density satisfy the condition of a relationship of X.ltoreq.(Y.times.Q)/(500.times.A).