An image forming apparatus having a heating unit control function in accordance with the present invention energizes one of a plurality of heating units designated by a sequence counter to be energized, halts energize of the heating unit if the time counter finishes the count of the heating period assigned to the heating unit, and halts the energization of the heating unit when a target temperature is reached by the temperature of the heating unit or the object to be heated by this heating unit even before the count of the heating period is completed by the time counter, and therefore the operation of heating the heating unit is efficient.