In this paper, we propose a new example of non-holonomic mobile robot, which we call the surface walker. This robot is composed of a hemisphere-shaped shell and a 2-d.o.f. mass-control device (pendulum) inside it, and undergoes the rolling contact constraint between the hemispherical surface of the robot and the ground. Unlike a lot of non-holonomic robots which have ever been researched, the drift term exists in the system of the hemisphere robot. First, we show basic concepts which the hemisphere robot has, and construct the kinetic model of this robot. Then we realize the locomotion control of the robot by periodically oscillating the internal pendulum and show its effectiveness by control experiments.