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 . <EOS>