An automatic analysis device, comprising: a test body container arranging mechanism in which a test body container is arranged and the arranged test body container is moved; a test reagent container arranging mechanism in which a test reagent container is arranged; a reaction container arranging mechanism in which a reaction container for reacting a test body with a test reagent is arranged; a test body sampling mechanism which suctions the test body from the test body container arranged in the test body container arranging mechanism, and discharges the test body to the reaction container arranged in the reaction container arranging mechanism; a test reagent sampling mechanism which suctions the test reagent from the test reagent container arranged in the test reagent container arranging mechanism, and discharges the test reagent to the reaction container arranged in the reaction container arranging mechanism; an optical analyzer which analyzes the test body in the reaction container arranged in the reaction container arranging mechanism; wherein the test body sampling mechanism includes a probe; an optical analyzer (25, 7) which analyzes the test body in the reaction container arranged in the reaction container arranging mechanism; a control unit which controls operations of the test body container arranging mechanism, the test reagent container arranging mechanism, the reaction container arranging mechanism, the test body sampling mechanism, and the test reagent sampling mechanism; and a probe guard for guarding said probe which is arranged in the test body container arranging mechanism, and includes a guard wall surrounding the test body sampling mechanism when the test body sampling mechanism is positioned on the test body container arranging mechanism, characterized in that said probe guard includes an outer circumferential wall and a retaining unit integrated with the outer circumferential wall and retained in an outer circumferential portion of the test body container arranging mechanism to be movable in a circumferential direction, wherein the test body container arranging mechanism includes a probe guard existence detecting sensor detecting a circumferential movement of the probe guard from a specific position, and the control unit stops a test body movement operation of the test body container arranging mechanism and a test body suction operation from the test body container of the test body sampling mechanism when the probe guard existence detecting sensor detects that the probe guard is moved from the specific position in said circumferential direction. a test body container arranging mechanism in which a test body container is arranged and the arranged test body container is moved; a test reagent container arranging mechanism in which a test reagent container is arranged; a reaction container arranging mechanism in which a reaction container for reacting a test body with a test reagent is arranged; a test body sampling mechanism which suctions the test body from the test body container arranged in the test body container arranging mechanism, and discharges the test body to the reaction container arranged in the reaction container arranging mechanism; a test reagent sampling mechanism which suctions the test reagent from the test reagent container arranged in the test reagent container arranging mechanism, and discharges the test reagent to the reaction container arranged in the reaction container arranging mechanism; an optical analyzer which analyzes the test body in the reaction container arranged in the reaction container arranging mechanism; wherein the test body sampling mechanism includes a probe; an optical analyzer (25, 7) which analyzes the test body in the reaction container arranged in the reaction container arranging mechanism; a control unit which controls operations of the test body container arranging mechanism, the test reagent container arranging mechanism, the reaction container arranging mechanism, the test body sampling mechanism, and the test reagent sampling mechanism; and a probe guard for guarding said probe which is arranged in the test body container arranging mechanism, and includes a guard wall surrounding the test body sampling mechanism when the test body sampling mechanism is positioned on the test body container arranging mechanism, characterized in that said probe guard includes an outer circumferential wall and a retaining unit integrated with the outer circumferential wall and retained in an outer circumferential portion of the test body container arranging mechanism to be movable in a circumferential direction, wherein the test body container arranging mechanism includes a probe guard existence detecting sensor detecting a circumferential movement of the probe guard from a specific position, and the control unit stops a test body movement operation of the test body container arranging mechanism and a test body suction operation from the test body container of the test body sampling mechanism when the probe guard existence detecting sensor detects that the probe guard is moved from the specific position in said circumferential direction.