The authors developed a high frequency response actuator which is used as an adaptor for a conventional electric discharge machine. With the adaptor, the effects of frequency response to machining stability and machining speed were examined. Experimental results show that machining speed was improved by roughly 1.5-2.5 for (1) the machining with fluid flushing on the finishing condition (10μmRmax) (2) the machining with jump action on the high-gloss finishing condition (1μmRmax) (3) the machining of the micro-hole (∅240μm). The machining speed for the machining with jump action on the finishing condition (10μmRmax), however, was not improved. The difference of the improvement in the machining speed is explained qualitatively by the difference of the behavior of debris in the machining gap.