To provide an image output system capable of changing job setting data stored in a storage device of an image output device from a computer.

When a job execution command is transmitted after transmission of job data from a personal computer 1 to a printer 2, image output processing based on the previously transmitted job data can be carried in the printer 2. The job data includes the job setting data (data on a paper size, the number of output, and the like), and the data are associated with an ID number and stored in a hard disk 22 as a job list file. The personal computer 1 is substantially provided with a list file acquisition command transmission part 14 transmitting a command for reading the job list file from the hard disk 22 and a job change command creation/transmission part 15 creating and transmitting a command for modifying the job setting data.