1. An image processing apparatus comprising: an image data storage unit configured to store image data; a job execution unit configured to execute an input job for inputting image data and storing the image data in the image data storage unit, and an output job for outputting the image data which is input by execution of the input job and is stored in the image data storage unit; a log storage unit configured to store log information of job executed by the job execution unit; and a controller configured to, in a case where the job executed by the job execution unit is the input job, store in the log storage unit the image data which is input by the execution of the input job as the log information of the input job, and in a case where the job executed by the job execution unit is the output job, store in the log storage unit reference information for referring to the image data stored in the log storage unit by the execution of the input job as the log information of the output job without storing in the log storage unit the image data output by execution of the output job.