An automatic analysis device comprising: a sample vessel for holding a sample; a reagent vessel for holding a reagent; a sample dispensing mechanism for dispensing the sample from the sample vessel; a reagent dispensing mechanism for dispensing the reagent from the reagent vessel; a reaction vessel for holding a mixed solution of the sample dispensed from the sample dispensing mechanism and the reagent dispensed from the reagent dispensing mechanism; an analysis unit that includes a plurality of reaction vessel placement units for placement of the reaction vessel therein, each of the plurality of reaction vessel placement units including a light source for emitting light to the reaction vessel holding the mixed solution and a light receiving unit for receiving the light emitted from the light source; an operating unit for input of information about the sample therein; and a control unit for controlling the analysis unit based on the input information, wherein the control unit is adapted, when information about a plurality of samples is input from the operating unit, to compare predicted reaction time lengths of analysis items requested for the plurality of samples, while determining an analysis order so that analyses of the analysis items are performed in descending order of the predicted reaction time length, to calculate a proportion of analysis items for which the predicted reaction time satisfies a predetermined condition for analysis items based on the result of the comparison of the predicted reaction time lengths of the analysis items requested for the plurality of samples, to calculate the number of the reaction vessel placement units where the analysis items for which the predicted reaction time satisfies the predetermined condition are preferentially analyzed among the plurality of reaction vessel placement units in the analysis unit based on the calculated proportion, and while controlling the analysis unit based on the determined analysis order, to control the analysis unit to give priority to and thus preferentially analyze the analysis items for which the predicted reaction time satisfies the predetermined condition in the calculated number of the reaction vessel placement units. a sample vessel for holding a sample; a reagent vessel for holding a reagent; a sample dispensing mechanism for dispensing the sample from the sample vessel; a reagent dispensing mechanism for dispensing the reagent from the reagent vessel; a reaction vessel for holding a mixed solution of the sample dispensed from the sample dispensing mechanism and the reagent dispensed from the reagent dispensing mechanism; an analysis unit that includes a plurality of reaction vessel placement units for placement of the reaction vessel therein, each of the plurality of reaction vessel placement units including a light source for emitting light to the reaction vessel holding the mixed solution and a light receiving unit for receiving the light emitted from the light source; an operating unit for input of information about the sample therein; and a control unit for controlling the analysis unit based on the input information, wherein the control unit is adapted, when information about a plurality of samples is input from the operating unit, to compare predicted reaction time lengths of analysis items requested for the plurality of samples, while determining an analysis order so that analyses of the analysis items are performed in descending order of the predicted reaction time length, to calculate a proportion of analysis items for which the predicted reaction time satisfies a predetermined condition for analysis items based on the result of the comparison of the predicted reaction time lengths of the analysis items requested for the plurality of samples, to calculate the number of the reaction vessel placement units where the analysis items for which the predicted reaction time satisfies the predetermined condition are preferentially analyzed among the plurality of reaction vessel placement units in the analysis unit based on the calculated proportion, and while controlling the analysis unit based on the determined analysis order, to control the analysis unit to give priority to and thus when information about a plurality of samples is input from the operating unit, to compare predicted reaction time lengths of analysis items requested for the plurality of samples, while determining an analysis order so that analyses of the analysis items are performed in descending order of the predicted reaction time length, to calculate a proportion of analysis items for which the predicted reaction time satisfies a predetermined condition for analysis items based on the result of the comparison of the predicted reaction time lengths of the analysis items requested for the plurality of samples, to calculate the number of the reaction vessel placement units where the analysis items for which the predicted reaction time satisfies the predetermined condition are preferentially analyzed among the plurality of reaction vessel placement units in the analysis unit based on the calculated proportion, and while controlling the analysis unit based on the determined analysis order, to control the analysis unit to give priority to and thus preferentially analyze the analysis items for which the predicted reaction time satisfies the predetermined condition in the calculated number of the reaction vessel placement units.