An interface control system overcomes deficiencies of by adopting a structure comprising host computers connected with peripheral devices, each host computer including a start-up status recognition unit and each peripheral device having a start-up status notification unit. The start-up status recognition unit receives information about start-up processing progress status of a peripheral device of interest, and peripheral device information including identification information about a parent device causing the peripheral device to perform start-up processing. The peripheral device information is transmitted to host computers by the start-up status notification unit of each peripheral device. Before a host computer causes a peripheral device to perform start-up processing, the start-up status recognition unit of the host recognizes the start-up status of the peripheral device in question on the basis of the received start-up processing status information and peripheral device information. Knowing the peripheral device start-up status allows the host computer to determine the necessity of starting up the peripheral device in question, whereby unnecessary start-up processing is averted and the efficiency of system operation is enhanced.