A method and apparatus for vacuum degassing blows gas into molten metal so as to form a substantially uniformly distributed bubble over the path area defined by an induction pipe. In order to achieve this, discharge nozzles are separated into at least two groups. The pressures of the gases discharged through the discharge nozzles in different groups are controlled independently of the other so that gas blown through a first group of nozzles forms bubbles at around the central portion of the induction pipe and the pressure of the gas blown through the other group of nozzles is adjusted for forming the bubbles in the vicinity of the periphery of the induction pipe.