An input/output control device is connected to an input/output switch which transfers a received input/output instruction to an input/output device whose local address is specified in the input/output instruction. The input/output control device includes a memory and circuitry. The memory stores specific information about a processor and a conversion table for converting a logical address of the input/output device into the local address, with the specific information and the conversion table each being associated with a device group that includes the processor and the input/output device. The circuitry identifies the device group based on the specific information about the processor of sender which information is obtained. The circuitry converts the logical address included in the input/output instruction into the local address which is obtained from the conversion table for the identified device group, and then sends the input/output instruction to the input/output switch.