A position adjustment device employs a holder on which a semiconductor wafer is attached. When placed on a surface plate, the wafer holder is turned upside-down, so that unlocked leg rods and the pattern transfer surface of the wafer are in direct contact with a reference surface of the plate. Piezoelectric elements are embedded in the holder as locking mechanism for the movable leg rods. In response to a variable DC voltage supplied by a voltage generating circuit, the piezoelectric elements deform to lock the rods with high accuracy.