At a data transfer device for transferring a request message from a first communication device to a second communication device, and transferring a response message containing a response data from the second communication device to the first communication device, an identifier to be allocated to the response data contained in the response message is generated according to a content of the response data, and a re-direct response message for re-directing the first communication unit to a URL containing the identifier is transmitted to the first communication device, instead of transmitting the response message, when the response message is received from the second communication device, and the response message containing the response data stored in the memory in correspondence to the identifier contained in the URL is transmitted when the request message for the URL containing the identifier is received from the first communication device.