PURPOSE: To reduce work, time and cost required for connecting channels and respective devices by generating a high load state without connecting a peripheral control device and a peripheral device to plural channels.

CONSTITUTION: An I/O control device is provided with a data transfer control part 10 for controlling data transfer between plural channel control parts 30 and a master device (main storage), a processor 20 for controlling the control part 10, a control storage part 40 storing firmware for driving the processor 20, a counter 50 for setting up the time interval of execution suppression, a subtractor 60 for subtracting the counter 50, and an execution suppressing circuit 70 for generating an execution suppressing signal to the processor 20 when the value of the subtractor 60 is turned to '0'.