A data processing device includes a receiving means, a discriminating means, a data retriever determining means, and a transmitting means. The receiving means receives data transmitted from a client computer to one of plural server computers. The discriminating means extracts destination information and source information from the received data. The destination information is information on the one of the plural server computers. The source information is information on the client computer. The data retriever determining means determines a data retriever in accordance with the extracted information. The data retriever searches the one of the plural server computers. The transmitting means transmits the data together with the destination information and the source information to the determined data retriever.