A PLC system construction support program for creating a system configuration diagram depicting a configuration of a PLC system constructed causes a computing terminal to function as: an image acquisition section that acquires image data of an image of the PLC system; a system configuration recognition section that creates system configuration information including arrangement information and selected unit information; a system configuration diagram generation section that creates a system configuration diagram based on the system configuration information; and a system configuration diagram editor section that performs display processing for displaying the system configuration diagram on a display section.