Abstract: Besides fixed display element information for merely displaying a fixed screen, variable display element information for variably displaying a variable display element whose display content changes, input element information representing the relationship of correspondence between the input means and an operation switch contained in a relevant component, and the operation program information for operating the relevant component as required, which are necessary for the relevant component to completely function as a component, are capable of being set and registered with respect to component data. In addition, the set and registered component is allowed to be handled in a component data unit when user screen data is generated. Accordingly, if the components are registered in a library, the possibility of use by a third party can be drastically increased, and the number of work steps during the screen generation by the user can be drastically decreased.