In a data processing device, an input form processing program is executed, and an input form obtaining unit obtains input form data for inputting data to be transmitted to a server. Transmission data processing description data included in the input form data and defining a method of accessing the server is passed from the input form obtaining unit to a transmission data processing unit, and UI description data displaying a user interface is passed to an UI processing unit. When the input data for each item included in the user interface is already input and stored, the UI processing unit extracts required input data from storing unit, and passes it to the transmission data processing unit via a data storing unit. The transmission data processing unit creates transmission data according to the defined access method and transmits it to the server.