To suppress evaporation of a reagent containing a specimen, and to prevent dropping of condensed water or contamination of a foreign matter, by opening/closing individually a cap of each dispensing reagent container.

This chemical analyzer has a plurality of reagent containers for storing the reagent or the specimen, a reagent container holding part for holding the plurality of reagent containers, a reaction container for reacting the reagent with the specimen therein, and a container holding part rotation means for rotating and stopping the reagent container holding part at an optional angle position. The analyzer includes; a pipetting mechanism for sucking the reagent or the specimen from the reagent container, and dispensing it into the reaction container; and a cap opening/closing mechanism for opening/closing individually each cap provided on the plurality of reagent containers, when sucking and dispensing by the pipetting mechanism.