Ball robot comprising a shell, a diametric main axle, at least one pendulum, and a drive mechanism comprising at least two drive motors, wherein the drive motors are arranged on the pendulum(s) in the vicinity of the inner surface of the shell. There is also provided a ball robot with a ball shaped shell, a diametric axle attached to the shell concentric with the main axis of rotation of the shell, and a drive mechanism located inside the shell and supported by the diametric axle, wherein the diametric axle is arranged to accommodate for dimensional changes of the shell along the main axis of rotation.