Die opening-closing means includes a servo motor and a movement conversion mechanism and is disposed between a support plate and a base stand. A movable plate is mounted on the support plate that is disposed on the base stand via a linear movement guide. In a forging cycle, die opening and closing is performed by activation of the die opening-closing means and tie bar fixing means at a rear surface side of the movable plate, and clamping force is obtained using a die clamping cylinder provided in the movable plate. When it is necessary to change over exclusive dies and change over is performed by: extending tie bar removal cylinders provided in a frame behind the movable plate so as to remove tie bars from a fixed plate; and moving a movable rail of internal rails to an open position and moving the change over carriage in along the internal rails from the outside.