This automatic analytical apparatus is provided with: a reaction container for mixing and reacting a sample and a test reagent; a measuring unit that irradiates a reaction solution in the reaction container with light, and measures the quantity of transmitted light or the quantity of scattered light; a control unit that processes a time series of light quantity data measured by the measuring unit; a storage unit for storing one or more approximation functions that approximate time series variation of the light quantity data; and an output unit that outputs the processing result of the control unit. The control unit selects any of the approximation functions stored in the storage unit, uses the selected approximation function to compute an approximation curve that represents time series variation of the light quantity data, computes divergence characteristic information on the basis of divergence information between the light quantity data and the approximation curve, and uses the divergence characteristic information to detect and classify anomalies contained in the light quantity data.