PURPOSE: To prevent an input/output control device from informing repeatedly busy and release status to a superior device by informing the status on release end to the superior device after the end processing of an inferior device is executed.

CONSTITUTION: When a start is received through a superior interface circuit 6 from a channel, a starting circuit 8 is operated, and a control adaptor, etc. are selected through an inferior interface circuit 7. A response signal to this selection is inputted to a busy release and interruption deciding circuit 11. If a busy release and interruption signal exists in the response signal, the circuit 11 is operated, a control adaptor resetting circuit 10 is operated to reset a using release and interruption flag and thereafter to operate a device end informing circuit 9. By the operation of this circuit 9, the status of the end is informed to the channel through the circuit 6. In this state, when an interrupting signal is sent, the circuit 9 informs the status of the end to a channel 2 through the circuit 6, thereafter, to execute the processing of an interruption.