PURPOSE: To improve response at the time of the change-over introduction of a liquid specimen, by providing the flow passage connected to a suction means and calibration liquid supply flow passages respectively connected to the upstream side of the flow passage in a branched state through opening/closing valves.

CONSTITUTION: The titled apparatus is equipped with the flow passage 2 connected to a suction pump 21 and a washing solution supply flow passage 3, calibration liquid supply flow passages 4, 5, a liquid specimen supply flow passage 6 and an air supply flow passage 7 respectively connected to the upstream side of said flow passage 2 through opening/closing valves 31, 41, 51, 61, 71 in a branched state while a flow analysis part 8 is provided to the downstream side of the flow passage 2. The flow passage 6 is provided to the rearmost stage of the other supply passages and an opening/closing valve 9 is provided between the flow passage 5 of the front stage and the flow passage 6. The connection arrangement of the flow passages 3W5, 7 other than the flow passage 6 to the flow passage 2 is set so that the flow passage 7 is set to the foremost state and the flow passages 3, 4, 5 are successively connected in succession thereto. At the time of use, either one of the valves 31, 41, 51, 61, 71 of the supply flow passages is opened but, by closing the valve 9 when the valve 61 of the flow passage 6 is opened, the carrying-in of a washing solution and a calibration liquid is prevented and measurement excellent in response can be performed.