A mass spectrometry device that can perform highly robust, highly sensitive, and low-noise analysis and addresses the problems of preventing reductions in ion transfer efficiency and of suppressing the introduction of noise components from droplets, etc. An ion source generates ions, a vacuum chamber is evacuated by an evacuation means and for analyzing the mass of ions, and an ion introduction electrode introduces ions into the vacuum chamber. The ion introduction electrode has an ion-source-side front-stage pore, a vacuum-chamber-side rear-stage pore, and an intermediate pressure chamber between the front-stage pore and the rear-stage pore, the cross-sectional area of an ion inlet of the intermediate pressure chamber is larger than the cross-sectional area of the front-stage pore, the position of the central axis of the front-stage pore and the position of the central axis of the rear-stage pore are eccentric, and the cross-sectional area of an ion outlet of the intermediate pressure chamber is smaller than the cross-sectional area of the ion inlet.