A bipedal robot of the present invention has a trunk consisting of an upper trunk and a lower trunk which are rotatable around a rotation axis relative to one another. The upper trunk has shoulders on the right and left sides. An arm is provided at each shoulder. A pair of right and left legs is attached to lower ends of the lower trunk. A storage battery is mounted to the back of the upper trunk, positioned within a shoulder width. The storage battery is positioned below the top of a head mounted on the upper trunk. When the robot walks a narrow passage or corridor having a width slightly larger than the width thereof, for example, this arrangement prevents the storage battery from interfering with the passage or the like.