In order to provide a static pressure air bearing having two axes usable in a vacuum environment in which the connection of the supporting air exhaust pipe does not adversely affect the motion of the bearing mechanism, air exhaust pipes are connected only with the fixed part(s) of the lower axis. Air exhaust from the upper axis is conducted through inner air exhaust piping (passages) formed within the fixed parts of the upper and lower axes, so that the exhaust pipes need not be connected with the movable parts.