A quality control system for a clinical examination automatic analyzer that analyzes patient specimens, the quality control system comprising: a memory mechanism configured to memorize patterns of variation over time of a combination of a quality control result (301, 302, 401, 402, 501, 502, 601, 602) of a measurement performed on a quality control substance by the clinical examination automatic analyzer and a calibration result (304, 306, 404, 406, 504, 506, 604, 606) of a calibration performed on the clinical examination automatic analyzer in a laboratory for a predetermined period of time; a comparison mechanism configured to compare one of the patterns of variation over time memorized in the memory mechanism with a pattern of variation over time of a combination of a quality control result (301, 302, 401, 402, 501, 502, 601, 602) of a measurement performed on a quality control substance by the clinical examination automatic analyzer and a calibration result (304, 306, 404, 406, 504, 506, 604, 606) of a calibration performed on the clinical examination automatic analyzer measured with the clinical examination automatic analyzer; and suggestion means configured to suggest optimum calibration intervals for the clinical examination automatic analyzer in accordance with a result of the comparison made by the comparison mechanism; wherein the suggestion means is also configured to suggest an optimum calibration method for the clinical examination automatic analyzer, and wherein the quality control system is configured to issue a precautionary note to indicate the necessity for additional calibration in accordance with the result of variation in a reagent that is derived from a same lot and used in other laboratories. a memory mechanism configured to memorize patterns of variation over time of a combination of a quality control result (301, 302, 401, 402, 501, 502, 601, 602) of a measurement performed on a quality control substance by the clinical examination automatic analyzer and a calibration result (304, 306, 404, 406, 504, 506, 604, 606) of a calibration performed on the clinical examination automatic analyzer in a laboratory for a predetermined period of time; a comparison mechanism configured to compare one of the patterns of variation over time memorized in the memory mechanism with a pattern of variation over time of a combination of a quality control result (301, 302, 401, 402, 501, 502, 601, 602) of a measurement performed on a quality control substance by the clinical examination automatic analyzer and a calibration result (304, 306, 404, 406, 504, 506, 604, 606) of a calibration performed on the clinical examination automatic analyzer measured with the clinical examination automatic analyzer; and suggestion means configured to suggest optimum calibration intervals for the clinical examination automatic analyzer in accordance with a result of the comparison made by the comparison mechanism; wherein the suggestion means is also configured to suggest an optimum calibration method for the clinical examination automatic analyzer, and wherein the quality control system is configured to issue a precautionary note to indicate the necessity for additional calibration in accordance with the result of variation in a reagent that is derived from a same lot and used in other laboratories.