A virtual reality or telereality (teleexistece) system which displays to an operator the changes in force senses caused by the variation of flow resistance of an electrorheological fluid by making the flow resistance, which is varied in response to the intensity of the electric field applied to the electrorheological fluid, cooperated in real time with an image (virtual world) generated by a computer or a really existing world (telereal world) connected through the intermediary of a robot.