After performing an analysis on a standard sample for a predetermined time, a plurality of ion optical elements such as an ion guide are sequentially selected one by one, and a direct-current voltage having a polarity different from that at the time of analysis is temporarily applied. Meanwhile, intensity data of ions having a specific m/z are continuously collected. After thus collecting the data, the ratio of the ion intensities before and after application of direct-current voltages having different polarities is calculated for each ion optical element, and it is determined whether or not the ratio is equal to or larger than a predetermined threshold value.