There are provided an image forming apparatus which implements divisional control using a plurality of control units without an increase in cost and a control method for the apparatus. To accomplish this, this image forming apparatus includes a master control unit that controls the overall image forming apparatus, a plurality of sub-master control units that control a plurality of functions for performing image formation, and a plurality of salve control units that control loads for implementing a plurality of functions. The master control unit is connected to the plurality of sub-master control units via first signal lines. The plurality of sub-master control units are connected to the plurality of slave control units via second signal lines higher in data transfer timing accuracy than the first signal lines.