In this paper, we describe a user-interface ( UI ) design support tool to design and evaluate multimodal UI easily. Multimodal UI designers meet the various requirement of system engineers and design panels ( panel-data ) and describe plan-goal scenarios ( process-data ). In the UI design support tool, first, designers construct panel-data by setting Ul-objects on a card, and then describe plan-goal scenarios linking a Ul-object with other cards. Designers are also able to test their multimodal UI on the tool. The UI design support tool offers devicemanager to handle multiple inputs and transforms all the multimodal inputs into an X windows events. The UI design support tool can be applied for various types of multimodal dialogue systems.