An error specifying method of specifying an error of an analyzer. The method specifies an error related to removal of a high-concentration reagent. The method includes a low-concentration reagent measuring step of performing an analysis process, which causes a composition to emit light, on a low-concentration reagent and measuring an amount of light emitted in order to acquire performance of the low-concentration reagent; a high-concentration reagent measuring step of performing the analysis process on the high-concentration reagent and measuring an amount of light emitted in order to acquire performance of the high-concentration reagent; and a reagent evaluating step of evaluating the performance of the low-concentration reagent and the performance of the high-concentration reagent based on the measurement results in the low-concentration reagent measuring step and the high-concentration reagent measuring step.