An automatic analyzer including: first reagent storing means (28, 29) for storing a plurality of reagent vessels; a reagent pipetting mechanism configured to pipette a reagent from a reagent vessel stored in the first reagent storing means; a measuring mechanism configured to allow the reagent and a sample to react with each other and measure such a reacting liquid; second reagent storing means for storing a plurality of reagent vessels; and a reagent vessel transfer mechanism capable of transferring a reagent vessel selected from the plurality of reagent vessels stored in the second reagent storing means to the first reagent storing means (28, 29); wherein the first reagent storing means (28, 29) has a cold storage function and the second reagent storing means has no cold storage function, and the automatic analyzer includes a a computer for controlling the automatic analyzer, characterised in that the computer performs the following steps: measure the elapsed placement time of each of the reagent vessels in the second reagent storing means, store a permissible placement limit value for the elapsed placement time of the reagent vessel in the second reagent storage means; and detect whether the measured elapsed placement time exceeds the permissible placement limit value, and control the reagent transfer means to transfer the reagent vessel to the first reagent storing means (28, 29) before the elapsed placement time for the reagent vessel will exceed the permissible placement limit value. first reagent storing means (28, 29) for storing a plurality of reagent vessels; a reagent pipetting mechanism configured to pipette a reagent from a reagent vessel stored in the first reagent storing means; a measuring mechanism configured to allow the reagent and a sample to react with each other and measure such a reacting liquid; second reagent storing means for storing a plurality of reagent vessels; and a reagent vessel transfer mechanism capable of transferring a reagent vessel selected from the plurality of reagent vessels stored in the second reagent storing means to the first reagent storing means (28, 29); wherein the first reagent storing means (28, 29) has a cold storage function and the second reagent storing means has no cold storage function, and the automatic analyzer includes a a computer for controlling the automatic analyzer, characterised in that the computer performs the following steps: measure the elapsed placement time of each of the reagent vessels in the second reagent storing means, store a permissible placement limit value for the elapsed placement time of the reagent vessel in the second reagent storage means; and detect whether the measured elapsed placement time exceeds the permissible placement limit value, and measure the elapsed placement time of each of the reagent vessels in the second reagent storing means, store a permissible placement limit value for the elapsed placement time of the reagent vessel in the second reagent storage means; and detect whether the measured elapsed placement time exceeds the permissible placement limit value, and control the reagent transfer means to transfer the reagent vessel to the first reagent storing means (28, 29) before the elapsed placement time for the reagent vessel will exceed the permissible placement limit value.