A device-sharing system easily shares devices in a network environment. When a device management server 100 receives a provide-service request, it identifies, based on service information, the network device 210 connected to the home gateway 200 and the network device 210 linked thereto to provide a service as service-related devices, and reads and returns service information for the service-related devices. When the gateway 200 receives the service information in reply to the provide-service request sent to the administration server 100, it displays a service list based on the received service information. When a service is selected from the displayed service list, the gateway relays communication between the device 210 connected to the gateway 200 and the identified service-related device based on the device-to-device communication information contained in the received service information for the selected service.