To provide a structure for attaining a more natural walking attitude like bipedal motion of a human being and a center of gravity movement method, in a bipedal walking robot.

The bipedal walking robot includes: a lower limb constituted of a waist part 4 and both legs; and an upper body constituted of an abdomen part 3 inclinable making the waist part as an axis and a chest part 2 connected with a head part 6 and both movable arms and having a structure rotatable making the abdomen part as an axis. A driving battery so-called as a balancer 42 and an auxiliary weight for moving the center of gravity so-called as a stabilizer 43 independently vertically movable in right/left direction, are mounted in a chest part box body. In the bipedal walking robot, the respective movable parts are made movable by an actuator 8, and the waist part is absolutely horizontally retained by a three-axis acceleration sensor 22 placed on the head part. Movement of the center of gravity in the front and rear sides is performed by forwardly inclined action or rearwardly inclined action of the upper body or position movement of the stabilizer in the box body of the chest part 2 or leg joint part action of both legs. Further, movement of the center of gravity in the right and left sides is performed by rotation action of the chest part making the abdomen part as an axis and composite action of the balancer and the stabilizer.