A power transmission shaft which transmits rotational energy of a flywheel is divided into a first shaft section adjacent to the flywheel and a second shaft section adjacent to a power take-off gear. A planetary gearing is arranged between the shaft sections and is adapted to be driven by a servo motor. A power take-off gear is mounted on an output section of the planetary gearing so as to transmit the power to drives. The servo motor controls the rotation of the output section of the planetary gearing to vary the rotation of the power take-off gear so that the action velocity of the slide or the like can be freely controlled and press working for different kinds of materials can be carried out.