In this paper, we propose the knowledgeable environment as a framework for integrated systems for human-machine co-existing space. In the knowledgeable environment, integration is achieved as knowledge-level communication and cooperation. We abstract all machines as information agents whose roles and communication are understandable for people. Ontology is here used as explicit representation of the abstraction of the environment which includes agents, objects, and activities of agents and people. Cooperation is also achieved by using ontology. We re-define concept of human-machine interaction in the light of knowledge-level interaction, i.e., interaction with various logical and spatial relation among participants.