AUTOMATED ANALYZER

Provided is an automatic analyzer that prevents different types of reagents from being misplaced and prevents reagents from being removed at wrong timing with less space and fewer components. A stopper 202 is installed at a position where the stopper 202 is in contact with an insertion direction front surface 302 of a reagent container 301A and 301B and prevents the reagent container 301A and 301B from being set before the reagent container 301A and 301B is joined to a piercing needle 205 and where the stopper 202 interferes with a holding surface of the reagent container 301A and 301B and prevents the reagent container 301A and 301B from moving in a slot 201 even if the reagent container 301A and 301B is attempted to be removed in a state where the reagent container 301A and 301B is joined to the piercing needle 205.