PURPOSE: To equalize a pressing force by providing a plate installed at the tip of a driving rod and plural hydraulic cylinders, arranged corresponding to plural metallic molds in the plate and mutually connected with a pipe.

CONSTITUTION: When a driving rod 108 is lowered, a piston rod (83a) of a hydraulic cylinder (80a) is brought into contact with a top force (3a). When the driving rod 108 is further lowered, the movement of the piston rod (83a) is stopped to move a liquid in a cylinder body (81a) through a pipe 72 to a cylinder body (81b). Thereby, the piston rod (83b) of the hydraulic cylinder (80b) is moved by a stroke of the driving rod 108. When both the piston rods (83b) and (83b) are brought into contact with a top and a bottom forces (3a) and (3b), the internal pressures of the cylinder bodies (81b) and (81b) are increased to pressurize preforms (1a) and (1b) in metallic molds (20a) and (20b). Since the pressures in the cylinder bodies (81a) and (81b) are always equal, the applied pressures acting on the respective preforms are equalized to afford the objective homogeneous glass lenses.