An ion trap includes: an ion trap including a plurality of electrodes; a rectangular voltage generator including a voltage source for generating a direct voltage and a switching section, the rectangular voltage generator configured to operate the switching section to generate a rectangular voltage by switching the direct voltage generated by the voltage source and to apply the rectangular voltage to at least one of the plurality of electrodes; and a switching section temperature controller configured to control a temperature of the switching section so as to maintain the temperature of the switching section at a target temperature which is higher than a highest reaching temperature of the switching section.