If a job executed on the data to be processed is stopped due to interruption of a wireless communication with an image processing apparatus and a portable terminal, which happens to occur while the image processing apparatus is receiving the data to be processed, which is transmitted by the portable terminal, the image processing apparatus examines if the portable terminals connected before and after stop of the job execution are one and the same, and requests the portable terminal to retransmit the data to be processed. And then the image processing apparatus resumes executing the job on the data to be processed, which is retransmitted in response to the request.