An automatic analyser, comprising: a reaction disk on which a plurality of reaction containers (31, 41) 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 (20, 30) on which a plurality of reagent containers are arranged; a reagent dispensing mechanism (60, 70) 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 (20, 30), the reagent dispensing mechanism (60, 70), 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 (31, 41) 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 (20, 30) on which a plurality of reagent containers are arranged; a reagent dispensing mechanism (60, 70) 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 (20, 30), the reagent dispensing mechanism (60, 70), 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.