The present invention discloses a forging apparatus comprising an oil hydraulic circuit (70) for supporting one or a plurality of punches to be selected from a plurality of punches (26, 28) by hydraulic pressure which is to be released prior to the arrival of a mould assembly (12) at a bottom dead center during forging process, wherein a punch member (40) is positioned at a mould holder (14), a bypass valve (50) being arranged at a punch holder (16) for switching on and off the flow path of the oil hydraulic circuit. The punch member moves a valve element (51) of the bypass valve along the direction which the valve is open prior to the arrival of the mould holder at the bottom dead center during the forging process so as to mechanically switch open the flow path of the oil hydraulic circuit.