PURPOSE: To simplify construction and facilitate maintenance, by providing a gas-separating part with a bent form, arranging this member in an exhaust gas chamber and furnishing openings on the inner periphery of the bent portion.

CONSTITUTION: A separator 10 is installed between gas chromatograph 2 and mass spectrometer 6 and a portion of its U-tube 12 is bent into a gas-separating part 14. This gas-separating part 14 is installed in a discharge gas chamber 16 provided with the required space 18 and an opening 20 is provided for connection with the inside space of the gas-separating part 14. By using this kind of separator for analysis of a specimen, a heavier specimen is led, by a centrifugal force, to the mass analyzer 6 along the outer periphery of the gas-separating part 14 and on the other hand, a lighter specimen is led along the inner periphery of the gas-separating part 14 and discharged through the opening 20.