PURPOSE: To prevent impact sound which occur when metallic materials are impacted and extend the life of the punch of a press machine, by constituting the ram in such a way that the ram is instantaneously stopped near the bottom dead center.

CONSTITUTION: A ram R is lifted upward or lowered downward by means of the rotary motion of a crank 12. When a crank shaft 10 which has been stopped near the bottom dead center of the ram R is moved and rotated through a driving mechanism composed of a cam, rocking board, etc., a shaft core C2 of an eccentric shaft section 10C moves upward. When the variation ratio of the rotation of the crank shaft 10 to the rotation of an eccentric ring 11 is adequately selected, therefore, condition where the ram R is temporarily stopped near the bottom dead center of the ram R is produced. When the descending inertia force of the crank 12 is instantaneously stopped near the bottom dead center of the ram R in this way, a punch P is stopped just before it contacts with a metallic plate X on a die D and impact sound which occur when the metallic material X is impacted by the punch P are prevented.