In recent years with the development of MEMS, various microactuators have been developed. In general, the smaller the actuator, the smaller its force becomes, but measurement of such small force is difficult and dependable instruments are not currently available. We developed a probe type sensor to measure very small forces using a semiconductor shear strain gauge of a cantilever type sensor. A highly sensitive, stable probe was created by using a good raw material, single crystal silicon, and by forming both the stress concentration part and the strain sensor on the same silicon crystal. We designed the probe using the finite element method, and invented a structure in which a very small force effectively generates strain on the sensor. We also developed a semiconductor micromachining process including an inducted coupled plasma deep trench etching method to manufacture the probe, and built a calibrator for the probe based on an electronic balance. In preliminary experiments, we successfully measured the force with as small as 1 mN resolution, precisely as designed by FEM. In future, we shall develop a probe with 1 (mu) N resolution.