To provide a gas spectrograph mass spectrometer (GC/MS) capable of smoothly introducing a capillary column into an ion source chamber and having a structure which prevents critical damage such as fracture etc. of the capillary column.

In the GC/MS apparatus, the capillary column drawn from a GC communicates with the inside of the ion source chamber of an MS via a guide tube for preventing breakage of the capillary column, and the guide tube is passed through a chamber for exhaust provided in the rear stage of the GC. A bored hole for evacuating the inside of the guide tube via the chamber for exhaust is provided above the guide tube located in the chamber for exhaust.