In this research, we propose the robot technology (RT) Ontology for Interactive Human-Space Design and Intelligence to make robot provide appropriate services according to situations. For this, we propose to define that "Main task" as a task that the user requests and "Tsuide task" as an essential task accompanied with the "Main task" to complete it. We focus on the development of the system for identifying and defining "Tsuide task" that is changed by the intention of user and the main task. We name the proposing technique as "RT Ontology" which can be used for the infrastructure technology for structuring space information. In this paper, we describe the outline of RT Ontology and experiments.