An automated analysis device comprising: a container transport device on which a plurality of reagent containers for accommodation of reagents used for analysis of a sample can be mounted; and a lid opening/closing mechanism that can simultaneously open or close lids of a plurality of specific reagent containers located at a dispensing/stirring position among the plurality of reagent containers, wherein the lid opening/closing mechanism includes: a unit base that is fixed to the container transport device, a hook base part that is rotatably linked to the unit base, a lid opening/closing drive device that moves the hook base part in parallel in an opening/closing direction of lids of the plurality of specific reagent containers with respect to the unit base, a plurality of hooks that are rotatably linked to the hook base part, and respectively engage with the lids of the plurality of specific reagent containers in a first orientation where the hook is oriented to engage with the lid, and a plurality of hook drive devices which can individually rotationally move the plurality of hooks with respect to the hook base part between the first orientation and a second orientation where the hook is oriented not to engage with the lid, and wherein each of the plurality of hooks includes: a claw portion that, when the hook is oriented to engage with a lid, causes force to act on the lid in the opening direction, and a basal part that, when the hook is oriented to engage with the lid, causes force to act on the lid in the closing direction, characterized in that each of the plurality of hooks further includes: an arm portion, the basal part being provided at a front end of the arm portion, a closing protrusion protruding in the horizontal direction from the front end of the arm portion and extending perpendicular to the basal part and in the horizontal direction from the end of the arm portion, wherein the closing protrusion is configured such that, when the hook is oriented not to engage with the lid, the closing protrusion causes force to act on the lid in the closing direction. a container transport device on which a plurality of reagent containers for accommodation of reagents used for analysis of a sample can be mounted; and a lid opening/closing mechanism that can simultaneously open or close lids of a plurality of specific reagent containers located at a dispensing/stirring position among the plurality of reagent containers, wherein the lid opening/closing mechanism includes: a unit base that is fixed to the container transport device, a hook base part that is rotatably linked to the unit base, a lid opening/closing drive device that moves the hook base part in parallel in an opening/closing direction of lids of the plurality of specific reagent containers with respect to the unit base, a plurality of hooks that are rotatably linked to the hook base part, and respectively engage with the lids of the plurality of specific reagent containers in a first orientation where the hook is oriented to engage with the lid, and a plurality of hook drive devices which can individually rotationally move the plurality of hooks with respect to the hook base part between the first orientation and a second orientation where the hook is oriented not to engage with the lid, and a unit base that is fixed to the container transport device, a hook base part that is rotatably linked to the unit base, a lid opening/closing drive device that moves the hook base part in parallel in an opening/closing direction of lids of the plurality of specific reagent containers with respect to the unit base, a plurality of hooks that are rotatably linked to the hook base part, and respectively engage with the lids of the plurality of specific reagent containers in a first orientation where the hook is oriented to engage with the lid, and a plurality of hook drive devices which can individually rotationally move the plurality of hooks with respect to the hook base part between the first orientation and a second orientation where the hook is oriented not to engage with the lid, and a claw portion that, when the hook is oriented to engage with a lid, causes force to act on the lid in the opening direction, and a basal part that, when the hook is oriented to engage with the lid, causes force to act on the lid in the closing direction, characterized in that each of the plurality of hooks further includes: an arm portion, the basal part being provided at a front end of the arm portion, a closing protrusion protruding in the horizontal direction from the front end of the arm portion and extending perpendicular to the basal part and in the horizontal direction from the end of the arm portion, wherein the closing protrusion is configured such that, when the hook is oriented not to engage with the lid, the closing protrusion causes force to act on the lid in the closing direction. an arm portion, the basal part being provided at a front end of the arm portion, a closing protrusion protruding in the horizontal direction from the front end of the arm portion and extending perpendicular to the basal part and in the horizontal direction from the end of the arm portion, wherein the closing protrusion is configured such that, when the hook is oriented not to engage with the lid, the closing protrusion causes force to act on the lid in the closing direction.