A quality control system comprising a plurality of analyzers and a control device connected to the analyzers via a network, the quality control system comprising: measurement units for measuring samples, the measurement units being provided in each of the analyzers; quality control data transmitting means for transmitting, to the control device via the network, quality control data obtained by the measurement units by measuring quality control samples, the quality control data transmitting means being provided in each of the analyzers; quality control data receiving means for receiving a plurality of quality control data sent from each of the quality control data transmitting means, the quality control data receiving means being provided in the control device; quality control means for implementing quality control based on the quality control data received by the quality control data receiving means, the quality control means being provided in the control device; calibration uncertainty memory for storing uncertainty of analyzer calibration for each of the analyzers; measurement uncertainty obtaining means for obtaining uncertainty of measurement of analyzer based on the uncertainty of analyzer calibration and the quality control data; quality control result output means for outputting a result of quality control obtained by the quality control means; and measurement uncertainty output means for outputting the uncertainty of measurement obtained by the measurement uncertainty obtaining means, characterized in that the uncertainty of calibration is configured to be calculated by combining a first uncertainty obtained by measuring an unknown sample whose measurement data are unknown by a first standard analyzer, a second uncertainty obtained by measuring the unknown sample by a second standard analyzer, a third uncertainty obtained by measuring a standard substance whose measurement data are known by the second analyzer and a fourth uncertainty obtained by measuring the standard substance by the analyzer for which the uncertainty of calibration is to be calculated. measurement units for measuring samples, the measurement units being provided in each of the analyzers; quality control data transmitting means for transmitting, to the control device via the network, quality control data obtained by the measurement units by measuring quality control samples, the quality control data transmitting means being provided in each of the analyzers; quality control data receiving means for receiving a plurality of quality control data sent from each of the quality control data transmitting means, the quality control data receiving means being provided in the control device; quality control means for implementing quality control based on the quality control data received by the quality control data receiving means, the quality control means being provided in the control device; calibration uncertainty memory for storing uncertainty of analyzer calibration for each of the analyzers; measurement uncertainty obtaining means for obtaining uncertainty of measurement of analyzer based on the uncertainty of analyzer calibration and the quality control data; quality control result output means for outputting a result of quality control obtained by the quality control means; and measurement uncertainty output means for outputting the uncertainty of measurement obtained by the measurement uncertainty obtaining means, characterized in that the uncertainty of calibration is configured to be calculated by combining a first uncertainty obtained by measuring an unknown sample whose measurement data are unknown by a first standard analyzer, a second uncertainty obtained by measuring the unknown sample by a second standard analyzer, a third uncertainty obtained by measuring a standard substance whose measurement data are known by the second analyzer and a fourth uncertainty obtained by measuring the standard substance by the analyzer for which the uncertainty of calibration is to be calculated.