The purpose of the present disclosure is to provide: a mass spectrometry device that can reduce a deviation in a mass axis due to the generation of heat from an AC voltage control circuit; and a method for controlling the mass spectrometry device. The mass spectrometry device according to the present disclosure: comprises a quadrupole electrode 111, to which an AC voltage is applied, and a control unit 100, that controls the voltage value of the AC voltage; and uses the quadrupole electrode 111 as a mass filter. Before a measurement, the mass spectrometry device applies the AC voltage of a prescribed amplitude V1 to the multipole electrode for a prescribed time T1, and a heating value J1 that is generated when the AC voltage of the prescribed amplitude V1 is applied to the multipole electrode for the prescribed time T1 is equivalent to a heating value that is generated when the AC voltage of the amplitude that is applied during the measurement is applied until a thermally steady state is reached (see fig. 3A ).