An automatic analyser, comprising: a reaction disk on which a plurality of reaction containers are arranged; a sample dispensing mechanism including a sample dispensing nozzle that sucks a sample contained in a sample container and ejects the sample to a reaction container arranged on the reaction disk ; a reagent disk on which a plurality of reagent containers are arranged; a reagent dispensing mechanism including a reagent dispensing nozzle that sucks a reagent contained in the reagent container and ejects the reagent to the reaction container arranged on the reaction disk ; a spectroscopic detector that detects light transmitting a solution contained in the reaction container ; a pressure sensor that detects internal pressure of the sample dispensing nozzle ; and a control unit that controls operations of the reaction disk , the sample dispensing mechanism , the reagent disk , the reagent dispensing mechanism , and the spectroscopic detector , wherein the control unit calculates a plurality of feature quantities from a waveform of the pressure detected by the pressure sensor , characterized in that the control unit calculates one output value from the plurality of feature quantities through a determination function f being defined as a linear combination of the feature quantities x1, x2, ... , xn: f = k 1 x 1 + k 2 x 2 + knxn + C , wherein k1, k2, ... , kn and C are parameters that are optimized such that it provides for an optimal separation of the n-dimensional data space, and determines whether or not the sample is normally sucked or ejected by the sample nozzle on the basis of the calculated one output value. a reaction disk on which a plurality of reaction containers are arranged; a sample dispensing mechanism including a sample dispensing nozzle that sucks a sample contained in a sample container and ejects the sample to a reaction container arranged on the reaction disk ; a reagent disk on which a plurality of reagent containers are arranged; a reagent dispensing mechanism including a reagent dispensing nozzle that sucks a reagent contained in the reagent container and ejects the reagent to the reaction container arranged on the reaction disk ; a spectroscopic detector that detects light transmitting a solution contained in the reaction container ; a pressure sensor that detects internal pressure of the sample dispensing nozzle ; and a control unit that controls operations of the reaction disk , the sample dispensing mechanism , the reagent disk , the reagent dispensing mechanism , and the spectroscopic detector , wherein the control unit calculates a plurality of feature quantities from a waveform of the pressure detected by the pressure sensor , characterized in that the control unit calculates one output value from the plurality of feature quantities through a determination function f being defined as a linear combination of the feature quantities x1, x2, ... , xn: f = k 1 x 1 + k 2 x 2 + knxn + C , wherein k1, k2, ... , kn and C are parameters that are optimized such that it provides for an optimal separation of the n-dimensional data space, and determines whether or not the sample is normally sucked or ejected by the sample nozzle on the basis of the calculated one output value. <EOS>