PURPOSE: To easily and surely identify the components of an unknown sample by determining the calibration curve to indicate the correspondence relation between the retention time values of the respective components of the gas chromatograph and mass chromatograph of a sample contg. known components from said holding time values.

CONSTITUTION: The sample mixed with the known component having specified retention time intervals is introduced into the gas chromatograph 2 and the respective components are detected by a gas detector 8. A gas chromatogram (a) is obtd. in a measuring and calculating part 12. The respective components subjected to the vapor phase sepn. of the sample mixture of the same components are introduced through an interface 6 into a mass analyzer 4. The ions subjected to mass sepn. in an ion detector 4 are detected and a mass chromatogram (b) is obtd. in the calculating part 12. The retention time with the respective components AWD is then calibrated between the two chromatograms (a), (b) and is preliminarily stored. The calibration data obtd. in such a manner is used for identifying the components of the unknown sample.