Micro-manipulation techniques have been greatly demanded in the field of IC packaging, micro electro mechanical systems (MEMS), and basic physics in recent years. In case of micro-manipulation, the influence of gravitational force becomes extremely small. The adhesional force is more significant for smaller objects. Electrostatic force is generally known to be effective for detachment of a microparticle as the repulsive force. In our earlier study, the electrostatic force generated by applied voltage and the voltage required for detachment have been theoretically analyzed using the boundary element method (BEM). The model used consists of a manipulation probe, a spherical micro-object, and a substrate plate. These object are all conductive. In the present study, the voltage for detachment of micro-sphere with 30 mum diameter is experimentally clarified. This result indicates good agreement with the prediction by BEM analysis, and gives us the voltage criterion for electrostatic detachment of a microparticle to establish the reliable technique of electrostatic micro-manipulation.