A micro force sensor was fabricated using a single ZnO belt coated with ultra thin Cr film. As a result of the piezoresistive effect of the ultra thin (in nano-scale) Cr film, the bending of the belt led to the change in the resistance of ultra thin Cr film. Based on the mechanics of the materials, the relationship between the deformation and the force was calculated, and a linear relationship between the bending force and the resistance of Cr thin film was deduced at small bending regions. Dielectrophoresis, focused ion beam (FIB) and sputtering were used in the process of the micro force sensor. The experimental results show that the resistance of Cr film is sensitive to the bending force and demonstrate the potential for developing a new class of stable and sensitive nano-sized structures for force sensing.