A method of generating scenarios using differential scenaro information is presented. Behaviors of normal scenarios of similar purpose are quite similar each other, while actors and data in scenarios are different among these scenarios. We derive the differential information between them and apply the differential information to generate new alternative/exceptional scenarios. Our method will be illustrated with examples. This paper describes (1) a language for describing scenarios based on a simple case grammar of actions, (2) introduction of the differential scenario, and (3) method and examples of scenario generation using the differential scenario.