We propose a technique for the measurement of the work of adhesion of microstructures by using the atomic force microscope (AFM). The AFM system using a heterodyne interferometer has been developed to investigate the adhesive force acting between the sharp probe and the sample. The adhesive force acting on the probe is obtained from the deflection of the micromachined cantilever, which is measured precisely by the heterodyne interferometry. The sensitivity for the measurement of the adhesive force is evaluated to be 20pN. The adhesive force was investigated by using the Si3N4 probe with the tip radius of 50nm and some kinds of materials used for micromachining process. When we use the SiO2 substrate and five kinds of solution: (i)H2O, (ii)C2H5OH, (iii)CH3COCH3, (iv)CCl4 and (v)KOH, the measured adhesive force are in the range from 10 to 100nN. The adhesive force generated by CH3COCH3 is the smallest. This fact is consistent with the result that the rinse with CH3COCH3 reduces the pinning influence of the surface-micromachined structures. Moreover, the effect of the surface roughness and the contact area on the adhesive force are examined, and the results are discussed from a point of view of the macroscopic adhesive theory.