Provided is an automated analysis device equipped with a lid opening/closing mechanism with which it is possible to selectively open or close lids of a plurality of reagent containers, as well as to close all of the lids of the plurality of reagent containers, regardless of their current open/closed state. Each of a plurality of hooks 102 rotatably linked to a hook base part 104 has: a claw portion 203 which, when oriented to engage with a lid 101, causes force to act on the lid 101 in the opening direction; a basal part 202 which, when oriented to engage with the lid 101, causes force to act on the lid in the closing direction; and a closing protrusion 201 which, when oriented not to engage with the lid 101, causes force to act on the lid in the closing direction.