Abstract: The present invention relates to an automatic in vitro diagnostic apparatus capable of automatically performing a series of examination processes including a pretreatment process for specific components included in a biological sample such as blood and urine. The apparatus of the present invention comprises a base frame 104; a cuvette tray 110 movable back and forth on the base frame 104, for mounting cuvette holders 10 accommodating a plurality of cuvettes arranged thereon alongside each other; a tube tray 120 movable back and forth on the base frame, for mounting tube holders 20 accommodating a plurality of sample tubes containing samples thereon; and a sampling operation unit 500 movable left and right on the base frame 104, for mixing a sample contained in the sample tube with a reagent, and dropping the mixed solution onto an analysis strip provided in the cuvette.