Abstract The resonant frequency and sensitivity of flexural vibration for an atomic force microscope (AFM) cantilever have been analyzed. A closed-form expression for the sensitivity of vibration modes has been obtained using the relationship between the resonant frequency and contact stiffness of cantilever and sample. The results show, that an AFM cantilever is more sensitive when the contact stiffness is lower and that the first mode is the most sensitive mode. However, the high-order modes become more sensitive than the low-order modes as the contact stiffness increases. As contact stiffness becomes larger, the effects of lateral contact stiffness on the resonant frequency and sensitivity are apparent. Furthermore, increasing the tip length can increase the resonance frequency and sensitivity of the AFM cantilever when the normal contact stiffness is greater.