A graphical user interface device includes an operation procedure information database, a display element information database, an operation determination section, a display element selection section, and an integrated procedure and display-element screen preparation section. Procedure information and a display item to be operated by an operator are registered in the operation procedure information database. The procedure information is text information forming an operation manual. The operation determination section determines a current operation step based on information given from an actual plant. The integrated procedure and display-element screen preparation section prepares a layout of an operation screen allowing the procedure information and the display item of the current operation step to be simultaneously displayed on a single screen of the input/output equipment.