A contact stylus-type displacement sensor is proposed for a surface form measurement of micro-structures. The stylus is supported by an air-bearing, thus it can be moved smoothly without friction between the stylus and the air-bearing. In order to reduce the measurement force, a novel controlling technique of a contact force has been developed. During the measurement one edge of the stylus is maintained contact with the measured surface by its own weight. Another end of the stylus is connected with a counter weight by a string and the stylus is hanging on the string in order to reduce the contact force between the edge of the stylus and the measured surface. Measuring force is estimated to confirm the effectiveness of the counter weight. Surface measurement of a steel ball is carried out using the developed air-bearing displacement sensor.