1. An interface apparatus, comprising: an image processor configured to pick up an image of a room in an indoor space by a plurality of stereo cameras, and to produce a picked up image within a visual field and a distance image based on an indoor coordinate system for each of the stereo cameras; a registration section configured to register an indoor object device and a position of the indoor object device in the indoor space; an object recognition section configured to extract recognition objects from the picked up image based on distance information from each of the stereo cameras, and to classify the extracted recognition objects, corresponding to a person, into a head portion and a hand sign pointed by the person in the indoor space; a personal identification section configured to identify the person based on the recognition result of the head portion and a stature of the person; and a hand sign identification section configured to issue a command for an indoor operation to operate the indoor object device corresponding to an object to be operated, based on a direction of the hand sign pointed by the person, a kind and movement of the hand sign, and the identity of the person identified by the personal identification section; a personal state monitoring section configured to acquire and store logs of all behavior of the person in the indoor space, wherein the personal state monitoring section is configured to previously register the behavior to be monitored for each individual person, in a personal behavior log database, the object recognition section is configured to note an object sequentially from the top side thereof along the height direction of the indoor space, and to recognize the object by clipping the object sequentially from the top side thereof, and the hand sign identification section is configured to utilize the personal behavior logs, corresponding to the registered behavior to be monitored for each individual person, for identification of the hand sign.