PURPOSE: To prevent the sharp reduction of separation property, by means of enabling the gas centrifugal separator to be operated with safety in an ideal state even when the pressures in the light gas pipings and in the heavy gas pipings of the centrifugal separators may be largely differentiated.

CONSTITUTION: In a gas centrifugal separating cascade composed by connecting separating element steps in parallel of a plurality steps to be subjected to introduce the light gas component to a product header P and to introduce the heavy gas component to a waiste header W respectively, by means of separating the gas to be separated introducing from a feed header F via a feed tube T by centrifuge in each gas centrifugal separators, contraction of area part B is subjected to be formed by means of compressing or bending the feed pipings or the heavy gas pipings at the one part of them of the each centrifugal separators. By such means, even when the pressures of both pipings X, Y, the flow conductance can be regulated by selves of X, Y, and the pressure level within the headers P, W can be equal, and the prescribed object can effectively be realized.