A freeze valve for a molten glass discharging nozzle is disposed at the bottom of a glass melting furnace. The freeze valve has at least two sets of temperature control units provided around the nozzle and arranged in series in the longitudinal direction of the nozzle, and an ejector for ejecting a high-pressure gas disposed at the lower end of the nozzle and adapted to eject the high-pressure gas toward the axis of the nozzle. Each of the temperature control units includes heating and cooling means so as to heat and cool independently both the upper and lower portions of the nozzle.