In an automatic analysis device, when an external force acts on a probe guard 26 in a horizontal direction, the probe guard 26 moves in a direction escaping from the external force around a center portion 47 of a test body container installing mechanism 1, and the probe guard 26 is separated from a fixed position. An outer circumferential wall 29 of the probe guard 26 invades a test body sampling mechanism track 28, and thus a risk that a sampling nozzle 23 of a test body sampling mechanism 5 invades the test body container installing mechanism 1 is avoided by the outer circumferential wall 29. When the probe guard 26 is separated from the fixed position, this is detected, and thus the operation of the test body sampling mechanism 5 and the test body container installing mechanism 1 is stopped.