Provided is a mass spectrometer capable of easy exchange of a measurement sample and suppressing a carryover. The mass spectrometer includes a mass spectrometry section, an ion source the internal pressure of which is reduced by a differential pumping from the mass spectrometry section and the ion source ionizes the sample gas, a sample container in which the sample gas is generated by vaporizing the measurement sample, a thin pipe that introduces the sample gas generated in the sample container into the ion source, an elastic tube of openable and closable that connects the sample container and the thin pipe, a pair of weirs that closes or opens the elastic tube so as to sandwich the elastic tube, and a cartridge that integrates the sample container, the thin pipe, and the elastic tube, and is detachable in a lump from a main body of the mass spectrometer.