The image forming apparatus includes a main assembly, a replacement unit detachably mounted on the main assembly, an identification unit configured to identify whether the replacement unit is a first unit mounted in advance in a shipment state of the image forming apparatus or is a second unit after replacement, a common signal line configured to transmit a signal from the identification unit and another signal; a memory unit mounted on the main assembly and configured to store control information for the first unit, and a control unit configured to control the first unit based on the control information of the first unit, wherein the control unit is switchable between an identification mode and a normal operation mode, and wherein the control unit switches control information of the replacement unit mounted on the main assembly depending on whether the replacement unit is the first unit or the second unit.