An automatic analyzer comprising: a housing configured to accommodate an analyzer configured to analyze a specimen; a cover provided to cover an upper side of a working surface which is an upper surface of the housing, and configured to be pivotally supported around a support shaft provided on one side of a rear side on the upper surface of the housing between a closed position and an open position in an upper-lower direction; and an interlock unit provided on a front side on the upper surface of the housing, and capable of preventing the cover rotating from the closed position to the open position, wherein the interlock unit includes: a hollow case provided on a lower side of an end of a front side at the closed position of the cover, and having a rectangular parallelepiped shape disposed at a position adjacent to a front surface of an inside of the housing; an operation member configured to be movably supported between a lock position and a lock release position on an upper surface of the case, and inhibiting rotation to the open position of the cover by engaging with a protruding portion provided on the end of the front side of the cover at the lock position; an electromagnetic driving unit configured to drive the operation member; and a driving connecting unit configured to connect the operation member to the electromagnetic driving unit and drive the operation member by conveying an operation of the electromagnetic driving unit to the operation member, the housing has a front surface opening provided at a position on the front surface of the housing corresponding to the interlock unit and covered with a front plate detachable from the housing, and the interlock unit is provided to be attachable and detachable to and from the housing via the front surface opening in a state where the front plate is detached. a housing configured to accommodate an analyzer configured to analyze a specimen; a cover provided to cover an upper side of a working surface which is an upper surface of the housing, and configured to be pivotally supported around a support shaft provided on one side of a rear side on the upper surface of the housing between a closed position and an open position in an upper-lower direction; and an interlock unit provided on a front side on the upper surface of the housing, and capable of preventing the cover rotating from the closed position to the open position, wherein the interlock unit includes: a hollow case provided on a lower side of an end of a front side at the closed position of the cover, and having a rectangular parallelepiped shape disposed at a position adjacent to a front surface of an inside of the housing; an operation member configured to be movably supported between a lock position and a lock release position on an upper surface of the case, and inhibiting rotation to the open position of the cover by engaging with a protruding portion provided on the end of the front side of the cover at the lock position; an electromagnetic driving unit configured to drive the operation member; and a driving connecting unit configured to connect the operation member to the electromagnetic driving unit and drive the operation member by conveying an operation of the electromagnetic driving unit to the operation member, a hollow case provided on a lower side of an end of a front side at the closed position of the cover, and having a rectangular parallelepiped shape disposed at a position adjacent to a front surface of an inside of the housing; an operation member configured to be movably supported between a lock position and a lock release position on an upper surface of the case, and inhibiting rotation to the open position of the cover by engaging with a protruding portion provided on the end of the front side of the cover at the lock position; an electromagnetic driving unit configured to drive the operation member; and a driving connecting unit configured to connect the operation member to the electromagnetic driving unit and drive the operation member by conveying an operation of the electromagnetic driving unit to the operation member, the housing has a front surface opening provided at a position on the front surface of the housing corresponding to the interlock unit and covered with a front plate detachable from the housing, and the interlock unit is provided to be attachable and detachable to and from the housing via the front surface opening in a state where the front plate is detached.