An automatic analysis device comprising: a housing that houses an analysis device; a work surface that is an upper surface of the housing; a cover that covers an upper side of the work surface and is axially supported to be rotatable about a support shaft between a closing position and an upwardly open opening position, the support shaft being provided on one side of the housing; and closing means for inhibiting the cover from being opened at the closing position, wherein the closing means includes a protrusion portion that protrudes from a front surface of the cover, a locking lever that is axially supported to be rotatable about a rotating support shaft and inhibits the cover from being opened by rotating in a direction from the work surface toward the protrusion portion to cause an engagement portion to engage with the protrusion portion, and driving means for driving the locking lever, characterized in that the protrusion portion protrudes rearward from the front surface of the cover, and a first gear is integrally formed with the locking lever, a second gear is provided in engagement with the first gear, the second gear has a connecting shaft and a connecting plate that has one end axially supported to be rotatable about the connecting shaft, a solenoid comprising a plunger is provided configured to drive the connecting plate via a connecting pin provided at an end of the plunger, the connecting plate has an end provided with a first spring peg portion, and a pull spring has one end hooked on the first spring peg portion, wherein the pull spring has the other end hooked on a second spring peg portion that is fixed to the housing, wherein the solenoid, the plunger, the connecting plate, the first gear, the second gear, and the pull spring form driving means for driving the locking lever. a housing that houses an analysis device; a work surface that is an upper surface of the housing; a cover that covers an upper side of the work surface and is axially supported to be rotatable about a support shaft between a closing position and an upwardly open opening position, the support shaft being provided on one side of the housing; and closing means for inhibiting the cover from being opened at the closing position, wherein the closing means includes a protrusion portion that protrudes from a front surface of the cover, a locking lever that is axially supported to be rotatable about a rotating support shaft and inhibits the cover from being opened by rotating in a direction from the work surface toward the protrusion portion to cause an engagement portion to engage with the protrusion portion, and driving means for driving the locking lever, characterized in that the protrusion portion protrudes rearward from the front surface of the cover, and a first gear is integrally formed with the locking lever, a second gear is provided in engagement with the first gear, the second gear has a connecting shaft and a connecting plate that has one end axially supported to be rotatable about the connecting shaft, a solenoid comprising a plunger is provided configured to drive the connecting plate via a connecting pin provided at an end of the plunger, the connecting plate has an end provided with a first spring peg portion, and a pull spring has one end hooked on the first spring peg portion, wherein the pull spring has the other end hooked on a second spring peg portion that is fixed to the housing, wherein the solenoid, the plunger, the connecting plate, the first gear, the second gear, and the pull spring form driving means for driving the locking lever.