A system for detecting and displaying an external force applied to a robot. Magnitude and direction of the detected external force are displayed by an image for visual and intuitive understanding. A robot system includes a robot; a detection section for detecting an external force applied to the robot; a conversion section for converting magnitude and direction of the external force detected by the detection section into a coordinate value of a three-dimensional rectangular coordinate system; an image generating section for generating a force model image representing the magnitude and direction of the external force by a graphic, with use of the coordinate value obtained by the conversion section; and a display section for three-dimensionally displaying the force model image generated by the image generating section.
