Scheduling work is easily achieved without the necessity of an operator paying special attention to the throughput and the type of each printer and the idle time when each printer is available. An arrow is obtained when the operator performs a drag operation such as to increase the length in the vertical axis direction of an initial arrow. The length in the horizontal axis direction of the arrow becomes shorter in response to the above-mentioned drag operation. In this scheduling, all of the three available devices are used. Accordingly, the printing of the job is completed in a short printing time. Further, an arrow is obtained by a drag operation for increasing the length in the horizontal axis direction of the initial arrow. This scheduling represents that the job is executed by one device, for example, having a throughput A among the three available devices.