To provide a metal mold device which forms an optical disk substrate which can laminate signal faces successfully each other, while not causing a burr vertically to a reading face opposite to the signal face of the optical disk substrate.

In a metal mold device for forming an optical disk substrate which is equipped with a periphery stamper holder 25 comprising a stamper pressing section 34 holding a peripheral edge section 26E of a stamper 26 arranged at a mirror face-plate 24, and an inner periphery section 33 which specifies the peripheral edge section 27E of molded article cavity 27, a projection section 35 of a cross-sectional acute angle which consists of a smooth surface which projects to a direction inside of the molded article cavity 27 toward the stamper pressing section 34 is formed to the inner periphery section 33 of a periphery stamper holder.