An automatic analysis apparatus capable of improving detection sensitivity is provided. An optimum photometer between a light-scattering photometer and an absorptiometer based on a concentration range may be decided. A standard solution is measured multiple times at a normal calibration and a calibration curve is created. Calibration curves are individually created for an absorptiometer and a light-scattering photometer from the minimum and maximum measured values of the concentrations of each standard solution. The upper and lower limits of a standard solution concentration are computed from the minimum/maximum calibration curves. Sensitivity may be computed by using calibration parameters. Whether to use a concentration by absorption or a concentration by scattered light is decided based on the computed sensitivity. The computed sensitivities are compared between the concentration by absorption and the concentration by scattered light, and the use of the concentration of a higher sensitivity is decided.