Automatic Analyzer

An automatic analyzer comprising:

• a reagent container installation portion configured to install a reagent container that contains a reagent used in an analysis;
• a joint portion configured to join a supply flow path connecting a position where the reagent is used with the reagent container installed in the reagent container installation portion to the reagent container;
• and
• a slot portion configured to introduce the reagent container to the joint portion, wherein
• the automatic analyzer comprises a stopper configured to prevent the installed reagent container from moving in the slot portion, and wherein
• the stopper is provided at a position where the stopper is in contact with an insertion direction front surface of the reagent container and prevents the reagent container from being installed before the reagent container is joined to the joint portion and where the stopper interferes with a holding surface of the reagent container and prevents the reagent container from moving in the slot portion even if the reagent container is attempted to be removed in a state where the reagent container is joined to the joint portion.