An operation device includes a display unit, an operation unit, a registration unit, a searching unit and a guide screen generator unit. When a registration command is input for a screen displayed on the display unit, specific information of that screen is registered in the registration unit. The operation unit is operated to select a screen, for which a command to display an access procedure is input, out of a list screen relating to information of registered screens. This causes the searching unit to search a route to access that screen from a higher ranked screen. The guide screen generator unit generates a guide screen showing an access procedure utilizing that route and causes the display unit to display the generated guide screen.