With the mode of the driving signal S1 according to Example 3 as described above, the potential of the first electrode 121 relative to the COM potential stays at the positive polarity potential (+5 V) from the time t1 to the time t8 ((6+1) vertical durations of the COM signal), stays at the negative polarity potential (?5 V) from the time t8 to the time t13 ((6?1) vertical durations of the COM signal), stays at the positive polarity potential (+5 V) from the time t13 to the time t18 ((6?1) vertical durations of the COM signal), and stays at the negative polarity potential (?5 V) from the time t18 to the time t25 ((6+1) vertical durations of the COM signal), as illustrated in FIG. 11. That is to say, in the AC signal substantially applied to the first electrode 121, the duration with positive polarity potential and the duration with negative polarity potential are equal to each other in unit of a duration of double of one period. In other words, the average of period of the AC signal applied to the first electrode 121 is an integral multiple (n times) of 6 of first period of the COM signal, and the AC signal in which a period of n×(6+1) and a period of n×(6?1) are repeated is applied to the first electrode 121. Note that the phase of the AC signal applied to the second electrode 122 and the third electrode 123, except for the first electrode 121, of the peripheral electrode 120 configured for ion trapping is shifted from the phase of the AC signal applied to the first electrode 121. However, the duration in which the polarity is the positive polarity and the duration in which the polarity is the negative polarity are similarly equal to each other in the unit of a duration of double of one period of the AC signal.
