KEIROKA[○!R] assistive system is assistive technology which can reduce fatigue or load of human workers and also can keep their physical performance. In this paper, the author describes the concept of KEIROKA assistive system and Smart Suit [○!R] as a concrete example of KEIROKA system. The assistive mechanism of Smart Suit and its design based on information and robot technology (IRT), biomechanics and ergonomics will be mentioned. Usage examples of Smart Suit will be also shown. The application of IRT on KEIROKA assistive system and its future prospects will be remarked.