An image forming apparatus includes a printing engine to form an image on a printing medium through printing processes, an engine frame to support the printing engine having a driving system to drive the printing engine, a high voltage power supply provided in a surface of the engine frame to apply a high voltage to at least one of units performing the printing processes, a main board provided in a surface of the engine frame adjacent to the surface having the high voltage power supply, and having a system engine controller to control the printing engine and a video controller to control a video signal, first and second main connectors respectively provided at lateral sides of the high voltage power supply and the main board adjacent to each other, and a connection control line to connect the first and second main connectors.