To reduce device contamination caused by an additive and rapidly switch between starting and stopping additive spraying, this ion analysis device is provided with an ion source for ionizing a substance to be measured, a spraying unit for atomizing and spraying a liquid including an additive that reacts with the substance to be measured toward the substance to be measured, a separation and analysisunit for separating and analyzing ions generated from reaction between the substance to be measured and the additive, a detector for detecting ions separated and analyzed by the separation and analysis unit, and a control unit for reducing the flow rate of the additive supplied to the spraying unit when the additive is not necessary.