PURPOSE: To obtain a portable GC-MS which does not require any carrier gas cylinder, has a small size and light weight, and can be operated for a sufficiently long time.

CONSTITUTION: The title GC-MS is constituted of a GC 1, MS 3, and interface 2 connecting the GC 1 and MS 2 to each other. A cryopump 5 is provided as a main evacuating means for evacuating the vacuum vessel of the MS 3. The gas line 11 connected to the upper space of the liquid helium container 6 of the cryopump 5 is connected to a carrier gas flowing passage 13. The helium gas generated from the liquid helium is supplied to the GC 1 as a carrier gas by operating the cryopump 5.