An automatic analyzer, comprising: a photomultiplier for measuring luminescence intensity of an object of measurement; sensitivity control means (401, 442, 443; 401, 451) for controlling the sensitivity of the photomultiplier; memory means (401, 121) having stored therein plural sensitivity control values (514, 515) for the sensitivity control means (401, 442, 443; 401, 451), and analytical curves associated respectively with the plural sensitivity control values (514, 515) and used to calculate a concentration of an analyte in the object of measurement; means for choosing from the plural sensitivity control values (514, 515) stored in the memory means (401, 121) depending on the object of measurement, said choosing means being adapted to switch between different sensitivity control values (514, 515) in a time-sequential manner; and means for obtaining photomultiplier signals of the same object of measurement at said different sensitivity control values (514, 515), characterized by: means for integrating said photomultiplier signals, excluding a background signal value obtained at the same sensitivity control value, with respect to time to obtain a resulting effective integration (543, 544) as a feature for each of said sensitivity control values (514, 515); and means for calculating the concentration of the analyte by using the one of the obtained features (543, 544) for which the analytical curve associated with the respective sensitivity control value (514, 515) has a higher linearity part around the feature. a photomultiplier for measuring luminescence intensity of an object of measurement; sensitivity control means (401, 442, 443; 401, 451) for controlling the sensitivity of the photomultiplier; memory means (401, 121) having stored therein plural sensitivity control values (514, 515) for the sensitivity control means (401, 442, 443; 401, 451), and analytical curves associated respectively with the plural sensitivity control values (514, 515) and used to calculate a concentration of an analyte in the object of measurement; means for choosing from the plural sensitivity control values (514, 515) stored in the memory means (401, 121) depending on the object of measurement, said choosing means being adapted to switch between different sensitivity control values (514, 515) in a time-sequential manner; and means for obtaining photomultiplier signals of the same object of measurement at said different sensitivity control values (514, 515), characterized by: means for integrating said photomultiplier signals, excluding a background signal value obtained at the same sensitivity control value, with respect to time to obtain a resulting effective integration (543, 544) as a feature for each of said sensitivity control values (514, 515); and means for calculating the concentration of the analyte by using the one of the obtained features (543, 544) for which the analytical curve associated with the respective sensitivity control value (514, 515) has a higher linearity part around the feature. means for integrating said photomultiplier signals, excluding a background signal value obtained at the same sensitivity control value, with respect to time to obtain a resulting effective integration (543, 544) as a feature for each of said sensitivity control values (514, 515); and means for calculating the concentration of the analyte by using the one of the obtained features (543, 544) for which the analytical curve associated with the respective sensitivity control value (514, 515) has a higher linearity part around the feature.