A device control system does not require changing the application in conjunction with changes in process content or changes in the type or specifications of a device. A style sheet database 81 stores a plurality of style sheets describing information conversion rules for XML documents. A communication interface 84 acquires output data from an application 41, and acquires an XML document 1 containing information specifying the target device to which the output data is output and an output style sheet. Based on the output style sheet, an XML document converter 85 converts the XML document 1 acquired from the communication interface 84 to an XML document 2 including device control information for the target device. A device-specific XML document input/output unit 86 outputs the XML document 2 acquired from the XML document converter 85 to the device control service 73, 75 corresponding to the target device.