Provided is a system 100 for monitoring an operating status of a chromatograph to determine whether or not an abnormality due to an external condition independent of the characteristics of a sample being analyzed is present in the operating status of the chromatograph. This system includes: an external-condition measurement device (pressure sensor 19A, column oven thermometer 19B and room temperature thermometer 19C) for performing a time-series of measurement of the external condition and for obtaining a series of external-condition-related data; an index value calculator 23 for calculating an index value based on the series of the external-condition-related data obtained through an analysis; and an index value storage (data storage 24) for storing the index value for the analysis, with the index value being linked with an analysis data obtained through the analysis.