An automatic analyzer comprising: a dispensing mechanism including a dispensing probe for dispensing a sample or a reagent into a reaction container and a quantitative pump for sucking and discharging the sample or the reagent through the dispensing probe, wherein the quantitative pump is configured to be driven for a variable driving period, which is a time between a drive start time and a drive end time of the quantitative pump, such that variable amounts of samples or reagents are sucked or discharged in accordance with the variable driving period; an analysis part for analyzing a sample in the reaction container; a pressure sensor configured for detecting pressure data in the dispensing probe at plural timings of a dispensing operation of the dispensing probe; and a signal processing unit, the signal processing unit being configured for: extracting feature variables from pressure data detected by the pressure sensor at reference times of said plural timings at a dispensing operation of the dispensing probe; calculating a statistical distance between predetermined reference pressure fluctuation data and the feature variables, and judging whether or not the dispensing operation of the dispensing probe is correctly executed by judging whether or not the calculated statistical distance is lower than a constant threshold value, characterized in that: said reference times are a first reference time which is the drive start time, and a second reference time which is the drive end time, and the predetermined reference pressure fluctuation data are the same regardless of the variable amounts of samples or reagents. a dispensing mechanism including a dispensing probe for dispensing a sample or a reagent into a reaction container and a quantitative pump for sucking and discharging the sample or the reagent through the dispensing probe, wherein the quantitative pump is configured to be driven for a variable driving period, which is a time between a drive start time and a drive end time of the quantitative pump, such that variable amounts of samples or reagents are sucked or discharged in accordance with the variable driving period; an analysis part for analyzing a sample in the reaction container; a pressure sensor configured for detecting pressure data in the dispensing probe at plural timings of a dispensing operation of the dispensing probe; and a signal processing unit, the signal processing unit being configured for: extracting feature variables from pressure data detected by the pressure sensor at reference times of said plural timings at a dispensing operation of the dispensing probe; calculating a statistical distance between predetermined reference pressure fluctuation data and the feature variables, and judging whether or not the dispensing operation of the dispensing probe is correctly executed by judging whether or not the calculated statistical distance is lower than a constant threshold value, extracting feature variables from pressure data detected by the pressure sensor at reference times of said plural timings at a dispensing operation of the dispensing probe; calculating a statistical distance between predetermined reference pressure fluctuation data and the feature variables, and judging whether or not the dispensing operation of the dispensing probe is correctly executed by judging whether or not the calculated statistical distance is lower than a constant threshold value, characterized in that: said reference times are a first reference time which is the drive start time, and a second reference time which is the drive end time, and the predetermined reference pressure fluctuation data are the same regardless of the variable amounts of samples or reagents. said reference times are a first reference time which is the drive start time, and a second reference time which is the drive end time, and the predetermined reference pressure fluctuation data are the same regardless of the variable amounts of samples or reagents.