A warming-up method for an electrophotography image forming apparatus. The warming-up method includes the steps of turning on a heat source when the image forming apparatus is turned on or when a wake-up event is generated in a power saving mode, driving an image fix-related driving body for rotating a heated roller and a pressing roller, thereby heating the rollers; driving a main driving body and rotating an OPC drum after driving the image fix-related driving body; and stopping the sub-driving body and the main driving body when surface temperature of the heated roller and surface temperature of the pressing roller reach an objective temperature, respectively, by means of heat from the heat source and rotation of the heated roller and the pressing roller.