To provide a technique of maintaining balance of a bipedal walking robot during movement.

A bipedal walking robot is made floating slightly, then, weight on the foot bottom is made into zero, center of gravity is not wobbled, burden on the legs for posture control is reduced and it enables smooth walking. Not an propeller which extrudes air but an propeller which has blades with two kinds of elevation angles which can efficiently utilizes the difference of atmospheric pressure (dynamic lift) like wings of an airplane and can fly is incorporated.