A measurement condition memory stores a CID gas condition table indicating a relation between the scan speed of a mass scan by a front-stage quadrupole mass filter and a CID gas supply pressure. If the scan speed is high, an influence of a decrease in speed of ions due to collisions with a CID gas inside a collision cell is relatively large. An appropriate CID gas supply pressure that reduces the decay of a peak waveform on a mass spectrum and makes the ion intensity as high as possible is examined in advance for each scan speed, and is stored in advance. During measurement of a target sample, if a precursor ion scan measurement mode or the like is designated, a CID gas supply pressure corresponding to the currently set scan speed is obtained based on the CID gas condition table, and the CID gas supplier is controlled.