Provided is a data processing system capable of decreasing the possibility of attack to the server, regardless of the presence or absence of vulnerability of a web browser. In response to the data input at the terminal 3, the center apparatus 2 transmits, to the terminal 3, a data input program for transmitting the input data to the center apparatus 2. The center apparatus 2 receives data to be processed and the URL of the server 1 from the terminal 3, accesses the received URL, and transmits the data to be processed to the server 1 by the HTTP protocol.