An image forming apparatus capable of reading a unique pattern of a toner bottle without using an expensive device, and of preventing the delay of the toner replenishment. A control unit controls a driving unit to rotate a toner bottle for replenishing toner and controls a reading unit to read a unique pattern of the toner bottle in conjunction with the rotation of the toner bottle, when receiving a toner replenishment signal in N-th time from a toner remaining amount detection unit after receiving the bottle detection signal from a bottle mounting detection unit.