An operation unit in a child device causes a main unit in the child device to execute a stand-alone job, and causes the main unit and a server device to execute a cooperating job. The main unit executes the stand-alone job every time it is requested, and generates and manages a stand-alone job log including stand-alone job log identification information. The server device controls the execution of stand-alone jobs included in the cooperating job based on a request for executing the cooperating job, and manages cooperating job identification information associated with the stand-alone job log identification information of the stand-alone jobs included in the cooperating job. The server device acquires the stand-alone job logs from the main unit and extracts the stand-alone job logs including the stand-alone job log identification information associated with the cooperating job identification information, to generate a cooperating job log corresponding to the cooperating job.