1. An image forming apparatus comprising: an apparatus main body including an original platform for placing thereon a target to be read out and image reading means for reading image information on the target to be read out, to which a replaceable component is detachably attached; and control means for determining suitability of the replaceable component, the control means driving the image reading means to optically scan the replaceable component, which has been placed on the original platform prior to being loaded into the apparatus main body, to read image information, and then judging whether or not the replaceable component is suitable for the image forming apparatus based on the reading result.