An automatic analyzer comprising a configuration for mounting a plurality of analytical reagent kits including a first analytical reagent kit and measuring a plurality of analysis items, wherein the automatic analyzer is configured such that the first analytical reagent kit can be used for: a. measuring an analysis item solely by the first analytical reagent kit; and b. measuring a plurality of interrelated analysis items using two or more analytical reagent kits including said first analytical reagent kit; wherein the automatic analyzer is further configured such that in preparing the two or more analytical reagent kits used for the plurality of interrelated analysis items, the two or more analytical reagent kits are managed, to be associated with one another with respect to a preparation process state from timing of mounting the two or more analytical reagent kits on the automatic analyzer until timing of starting an analysis of an unknown sample, wherein each of the two or more analytical reagent kits include a magnetic particle reagent container containing a magnetic particle reagent; wherein said management includes collectively executing a registered preliminary preparation operation including a reagent capacity check and stirring of the magnetic particle reagent to all the analytical reagent kits used for the interrelated analysis items at timing at which all analytical reagent kits used for the interrelated analysis items are mounted; wherein in calibrating a calibration curve related to each analytical reagent kit used for the plurality of interrelated analysis items, when a calibration condition for an analysis item performed solely by the first analytical reagent kit is identical to a calibration condition for the first analytical reagent kit used for the plurality of interrelated analysis items, the automatic analyzer is configured such that a calibration result of the analysis item performed solely by the first analytical reagent kit is reused as a calibration result of the first analytical reagent kit used for the interrelated analysis items, wherein in mounting the first analytical reagent kit among the analytical reagent kits used for the plurality of interrelated analysis items on the automatic analyzer, the automatic analyzer is configured to determine whether a process of registering the first analytical reagent kit to the automatic analyzer can be executed on the basis of whether a second analytical reagent kit other than the first analytical reagent kit used for the plurality of interrelated analysis items is mounted. a. measuring an analysis item solely by the first analytical reagent kit; and b. measuring a plurality of interrelated analysis items using two or more analytical reagent kits including said first analytical reagent kit; wherein the automatic analyzer is further configured such that in preparing the two or more analytical reagent kits used for the plurality of interrelated analysis items, the two or more analytical reagent kits are managed, to be associated with one another with respect to a preparation process state from timing of mounting the two or more analytical reagent kits on the automatic analyzer until timing of starting an analysis of an unknown sample, wherein each of the two or more analytical reagent kits include a magnetic particle reagent container containing a magnetic particle reagent; wherein said management includes collectively executing a registered preliminary preparation operation including a reagent capacity check and stirring of the magnetic particle reagent to all the analytical reagent kits used for the interrelated analysis items at timing at which all analytical reagent kits used for the interrelated analysis items are mounted; wherein in calibrating a calibration curve related to each analytical reagent kit used for the plurality of interrelated analysis items, when a calibration condition for an analysis item performed solely by the first analytical reagent kit is identical to a calibration condition for the first analytical reagent kit used for the plurality of interrelated analysis items, the automatic analyzer is configured such that a calibration result of the analysis item performed solely by the first analytical reagent kit is reused as a calibration result of the first analytical reagent kit used for the interrelated analysis items, wherein in mounting the first analytical reagent kit among the analytical reagent kits used for the plurality of interrelated analysis items on the automatic analyzer, the automatic analyzer is configured to determine whether a process of registering the first analytical reagent kit to the automatic analyzer can be executed on the basis of whether a second analytical reagent kit other than the first analytical reagent kit used for the plurality of interrelated analysis items is mounted.