A method of handling a reagent container in an automatic analyser enabling automatic replacement of a reagent during analysis comprising the steps of: requesting an analysis by an operator; confirming whether a reagent container to be used for the analysis exists on a reagent driving disk ; if the reagent container to be used for the analysis is not set on the reagent driving disk , confirming whether a vacant position is present on the reagent driving disk ; characterised by : if no vacant position exists on the reagent driving disk but a vacant position exists on a fixed disk , moving by means of a reagent container moving unit one reagent container from the reagent driving disk to the fixed disk in order to make the vacant position on the reagent driving disk ; if no vacant position exists on either of the reagent driving disk and the fixed disk , moving by means of the reagent container moving unit one reagent container from the reagent driving disk to a loading system in order to make the vacant position on the reagent driving disk ; and if a vacant position exists on the reagent driving disk , moving by means of the reagent container moving unit a reagent container containing the reagent to be used for the analysis from the fixed disk onto the vacant position of the reagent driving disk . requesting an analysis by an operator; confirming whether a reagent container to be used for the analysis exists on a reagent driving disk ; if the reagent container to be used for the analysis is not set on the reagent driving disk , confirming whether a vacant position is present on the reagent driving disk ; characterised by : if no vacant position exists on the reagent driving disk but a vacant position exists on a fixed disk , moving by means of a reagent container moving unit one reagent container from the reagent driving disk to the fixed disk in order to make the vacant position on the reagent driving disk ; if no vacant position exists on either of the reagent driving disk and the fixed disk , moving by means of the reagent container moving unit one reagent container from the reagent driving disk to a loading system in order to make the vacant position on the reagent driving disk ; and if a vacant position exists on the reagent driving disk , moving by means of the reagent container moving unit a reagent container containing the reagent to be used for the analysis from the fixed disk onto the vacant position of the reagent driving disk . if no vacant position exists on the reagent driving disk but a vacant position exists on a fixed disk , moving by means of a reagent container moving unit one reagent container from the reagent driving disk to the fixed disk in order to make the vacant position on the reagent driving disk ; if no vacant position exists on either of the reagent driving disk and the fixed disk , moving by means of the reagent container moving unit one reagent container from the reagent driving disk to a loading system in order to make the vacant position on the reagent driving disk ; and if a vacant position exists on the reagent driving disk , moving by means of the reagent container moving unit a reagent container containing the reagent to be used for the analysis from the fixed disk onto the vacant position of the reagent driving disk . <EOS>