Active microvibration control systems have been developed and applied in a practical manner. Various types of actuator, for example an air actuator, a linear moving actuator, a piezoelectric (PZT) actuator and a giant-magnetostrictive (GMS) actuator, have been used. In general, all actuators have both merits and demerits, so an optimal actuator should be selected based on the objective performance and the conditions of usage. We developed an active 6-DOF microvibration control system using GMS actuators. It has been speculated that the GMS actuator is suitable as a displacement actuator for an active microvibration control. The reasons for this are that it has better durability and reliability compared with a PZT actuator, and also its response to an input signal is much faster than an air actuator. However, the demerits of the GMS actuator come to light through practical application of the system. The displacement property tends to decrease with increase in the magnitude of forced axial load, and it cannot generate a sufficient displacement in a low frequency range. Therefore, in order to improve the above-mentioned demerits related to a GMS actuator and an air actuator, we have developed a new type of hybrid actuator using a GMS actuator and an air actuator. The two actuators are arranged in parallel. This structural feature enables the new hybrid actuator to make up for both of the single actuators' demerits. Consequently, it has become possible to control displacement in the wider frequency range of 0.1-100 Hz and to generate a maximum displacement of more than 1 mm. This paper presents an outline of the experimental new hybrid actuator, the result of a dynamic characteristic test of the actuator and simulation analysis on the uni-axial microvibration control device using the hybrid actuator. Through these results, the higher performance achieved by the newly developed hybrid actuator is verified.