PURPOSE: To lock an air slider member to a guide rail member quickly and surely by pushing upper and lower surfaces of the guide rail member using the respective tips of piezo elements, and by fixing the air slider member to the guide rail member using this pushing force through the piezo elements.

CONSTITUTION: When an X slider 14 has stopped at a stop position of a guide rail 12, piezo elements 42A to 42F are driven by reverse piezoelectricity effect through a driver 45A of a controller 45 and cables 44AW44F, and the respective tips of the piezo elements 42AW42F abut on the upper surface 12a and the lower surface 12b of the guide rail 12. Thus, the X slider 14 can be fixed to the guide rail 12 by the pushing force of the piezo elements 42AW42F. So, the X slider 14 can be fixed to the guide rail 12 only by applying voltage on the piezo elements 42AW42F. Thus, it is possible to lock the X slider 14 quickly and surely.