An automatic analyzer comprising: a probe configured to pass through a cap of a capped vacuum blood collection tube, to suck a specimen inside the vacuum blood collection tube, and to discharge the specimen into a reaction cuvette; a syringe configured to cause the probe to suck and discharge the specimen; a dispensation flow path connecting the syringe; a pressure sensor arranged in the dispensation flow path and configured to detect an inner pressure of the probe at time of suction of the specimen as a pressure waveform; a memory configured to store therein a plurality of sets of clogging detection parameters (x nk, x' nk) in accordance with pressure in the vacuum blood collection tube for a suction amount of the specimen; and a controller configured to select the set of clogging detection parameters (x nk, x' nk) stored in the memory in accordance with the pressure in the vacuum blood collection tube and to perform clogging determination of the probe based on the selected set of clogging detection parameters (x nk, x' nk) and the inner pressure at the time of suction of the specimen detected in the pressure sensor, characterized by further comprising: a vacuum blood collection tube with a negative inner pressure; wherein each of the sets of clogging detection parameters (x nk, x' nk) is a set of known data prepared in advance, having n events has k characteristic variables and is to be used to calculate a statistical distance between the set of clogging detection parameters (x nk, x' nk) selected by the controller and target data, wherein the target data are derived from the pressure waveform of the inner pressure at the time of suction of a specimen targeted for the clogging detection and consists of respective characteristic variables (y 1, y 2,... y k) and, wherein the controller is configured to compare the statistical distance with a threshold value to perform the clogging determination of the probe. a probe configured to pass through a cap of a capped vacuum blood collection tube, to suck a specimen inside the vacuum blood collection tube, and to discharge the specimen into a reaction cuvette; a syringe configured to cause the probe to suck and discharge the specimen; a dispensation flow path connecting the syringe; a pressure sensor arranged in the dispensation flow path and configured to detect an inner pressure of the probe at time of suction of the specimen as a pressure waveform; a memory configured to store therein a plurality of sets of clogging detection parameters (x nk, x' nk) in accordance with pressure in the vacuum blood collection tube for a suction amount of the specimen; and a controller configured to select the set of clogging detection parameters (x nk, x' nk) stored in the memory in accordance with the pressure in the vacuum blood collection tube and to perform clogging determination of the probe based on the selected set of clogging detection parameters (x nk, x' nk) and the inner pressure at the time of suction of the specimen detected in the pressure sensor, characterized by further comprising: a vacuum blood collection tube with a negative inner pressure; wherein each of the sets of clogging detection parameters (x nk, x' nk) is a set of known data prepared in advance, having n events has k characteristic variables and is to be used to calculate a statistical distance between the set of clogging detection parameters (x nk, x' nk) selected by the controller and target data, wherein the target data are derived from the pressure waveform of the inner pressure at the time of suction of a specimen targeted for the clogging detection and consists of respective characteristic variables (y 1, y 2,... y k) and, wherein the controller is configured to compare the statistical distance with a threshold value to perform the clogging determination of the probe. a vacuum blood collection tube with a negative inner pressure; wherein each of the sets of clogging detection parameters (x nk, x' nk) is a set of known data prepared in advance, having n events has k characteristic variables and is to be used to calculate a statistical distance between the set of clogging detection parameters (x nk, x' nk) selected by the controller and target data, wherein the target data are derived from the pressure waveform of the inner pressure at the time of suction of a specimen targeted for the clogging detection and consists of respective characteristic variables (y 1, y 2,... y k) and, wherein the controller is configured to compare the statistical distance with a threshold value to perform the clogging determination of the probe.