The present invention relates to an image forming apparatus that minimizes the consumption of power during physical formatting of the hard disk drive or the deletion of data therefrom and to a control method thereof. The image forming apparatus has a non-volatile storage unit that stores image data and a controller that executes at least one of the operations of initialization of the storage unit and deletion of the image data stored in the storage unit, and further includes as operating modes an image forming mode during which image formation is enabled and a power-saving mode during which power consumption is minimized, wherein the controller switches the operating mode to power-saving mode when initialization processing or image data deletion processing is begun.