An image forming apparatus and a method of controlling the image forming apparatus are provided. The method includes receiving a reflection signal corresponding to a transmission signal transmitted from the image forming apparatus to a user sensing area, the reflection signal being reflected from a user, determining a distance between the image forming apparatus and the user, based on the received reflection signal, selecting a power consumption mode corresponding to the determined distance from among a plurality of power consumption modes, based on the distance between the image forming apparatus and the user, and performing user authentication or power control according to the selected power consumption mode.