When a specimen from a specimen ionizing unit is not sufficiently ionized, is caused to remain in sites other than a pore in an introducing section and be deposited as a product such as an oxide or carbide, which causes a deterioration in the performance of the mass spectrometry device. The mass spectrometry device has a specimen ionizing section for ionizing a specimen, a specimen-introduction regulating chamber into which ions of the ionized specimen are introduced, a differential evacuation chamber located downstream of the specimen-introduction regulating chamber, and an analyzing section located at the downstream side of the differential evacuation chamber, in which a discharge generating means is formed for generating an electric discharge inside the specimen-introduction regulating chamber and/or the differential evacuation chamber. The discharge generating means has a specimen introducing section electrode and a first-pore-section-forming member located oppositely to each other inside the specimen-introduction regulating chamber.