PURPOSE: To move a robot forward and backward and to turn it right and left with one motor together with action accompanying the feeling of reality concerning the robot to be used for a toy or a game device.

CONSTITUTION: Concerning the bipedalism robot composing parallel leg links 20 on both sides of a body part 1 of leg members at their lower ends, provided with a crank shaft 10 at the body part and provided with a leg rod 30 to be rotated by that crank shaft and wheels 40 at their lower ends, the main rod of the crank shaft is a hollow pipe, a reciprocative rod 11 is passed inside, cams 11a are fixed on both sides while inverting phases at right and left sides and further, a transmission gear 13 is pivotally supported to a crank pin 12 on the outside. When the crank shaft is revolved forward, the reciprocative rod is reciprocatively moved between both the transmission gears but when it is stopped or revolved backward, the cam protruding the reciprocative rod at the time of stop transmits the revolution. Further, a leg rod is provided with a slide plate 32 which upper and lower ends are rack gears and by sliding it, the revolutions of the transmission gears are transmitted to the wheels.