An image forming apparatus includes a volatile memory and System-on-Chip (SoC) part. The SoC part includes an internal memory, a CPU for accessing the volatile memory in the normal mode; an interface part for receiving a external signal, and a control part for, when the interface part has no input during a first preset time, copying information stored to the volatile memory to the internal memory and converting to a first power saving mode to lower an operating frequency of the volatile memory and an operating frequency of the CPU, and when a normal mode switch signal is not input during a second preset time in the first power saving mode, controlling the CPU to access the information copied to the internal memory and converting to a second power saving mode to change the volatile memory to a self-refresh mode.