An automated analyzer has a reaction disk on which a plurality of reaction vessels capable of holding sample and reagent mixtures can be placed, a first cover for covering at least a portion of the area above the reaction disk, a second cover that can be opened and closed independently from the first cover, at least one sensor for monitoring the opening and closing of the first cover, and a control unit for monitoring a signal from the sensor and carrying out control such that if the first cover has not been opened and closed during the period until a new analysis operation is started, a pre-analysis cleaning operation, blank measurement operation, or both, are skipped.