A method of controlling power consumption of an image forming apparatus includes outputting information regarding power consumption of a plurality of operation units if a power consumption check mode is set, performing power save operation in which at least one operation unit from among the plurality of operation units is turned on and the remaining operation units are turned off if a power save mode is set. Accordingly, on/off of the plurality of operation units may be controlled in the power save mode based on power consumption of each of the operation units.