The present invention is aimed at detecting an operator'sheight and position of each body part with a certain range ofaccuracy, which is used for calculation of a BMI value oroperation of a game. An exercise assist device (101) isprovided with a horizontal bar (102), a bar support (103) tosupport the bar, and a floor mat (104) on a surface of its body.A video camera (201) is mounted on the top of a monitor (701)as illustrated, for example, in Fig. 7 and captures the operatoras well as the horizontal bar (102) and bar support (103) inone image. Since the horizontal bar (102) and bar support (103)together with the operator are captured in one image, theybecome a three-dimensional measurement reference, so that theoperator's height can be calculated from the captured image.
