This invention provides an image forming apparatus for accurately specifying the type of the apparatus without increasing cost, and a method of controlling the same. To accomplish this, an image forming apparatus of the embodiment executes a continuous image formation test to specify the model of the self apparatus when a system control unit is connected to an engine control unit. In the continuous image formation, the image forming apparatus measures the period from synchronization signal output by the engine control unit to output of the next print start request by the system control unit, and specifies the model of the self apparatus in accordance with the measured period.