A reagent dispensing mechanism (15), first and second dispensing-mechanism transfer means (26, 27), and a second reagent vessel (reagent cassette) carrying-in/out mechanism (24), which are constructed by employing an XY-mechanism, are arranged so as to travel above a reagent table (25) to carry in/out a reagent cassette (22). As compared with the case where the reagent cassette carrying-in/out mechanism (24) is installed radially of the reagent table (25), the area of an automatic analyzer in the horizontal direction can be reduced and a reagent vessel (16) can be moved to a predetermined position in a shorter time by combining the rotation of the reagent table (25) with the movement of the XY-mechanism. Further, as compared the case of dispensing reagents from reagent vessels in a matrix pattern by using the reagent dispensing/transferring mechanism, the travel distance of the transferring mechanism can be shortened and so can be the travel time. Thus, an analyzer adaptable as a machine of high processing capability with a shorter cycle time can be constructed.