A mass spectrometer comprising a passage through which a sample solution flows, the passage including a capillary having an open tip, the sample solution flowing through the capillary out of the open tip of the capillary, a gas passage which forms a gas flow around the open tip of the capillary, the gas flow spraying the sample solution flowing out of the open tip of the capillary, a first electrode which contacts the sample solution flowing in the passage and applies an electric potential to the sample solution flowing in the passage, a second electrode disposed around the capillary near the open tip of the capillary, the second electrode being downstream from the first electrode with respect to a direction in which the sample solution flows in the passage, there being no gap extending downstream from the open tip of the capillary to the second electrode in a direction in which the sample solution flows out of the open tip of the capillary, the second electrode being electrically isolated from the sample solution flowing in the capillary and applying an electric field to the sample solution flowing in the capillary, and an analyzer which analyzes a mass of gaseous ions formed from the sample solution sprayed by the gas flow.