A pressure sensor detects the inner pressure of a probe at the time of suction of a specimen and a memory stores therein a plurality of clogging detection parameters in accordance with pressure in the vacuum blood collection tube. The clogging detection parameter stored in the memory is selected in accordance with the pressure in the vacuum blood collection tube, and a determination of the clogging of the probe is performed based on the selected clogging detection parameter and the inner pressure at the time of suction of the specimen detected in the pressure sensor.