A blood coagulation analyzer comprising: a reaction container which allows a reaction to occur in a liquid mixture of a sample and a reagent; a light source configured to irradiate the reaction container with single-wavelength light; and a plurality of detectors (103a, 103b) arranged around the reaction container at different angles with respect to an optical axis of the light source for detecting scattered light emitted from the liquid mixture of the sample and the reagent in the irradiated reaction container, the blood coagulation analyzer configured to calculate a blood coagulation time from chronological light intensity variation data detected by the detector (103a, 103b), wherein: the blood coagulation analyzer acquires and stores multiple pieces of light intensity variation data each corresponding to a respective one detector among the plurality of detectors (103a, 103b), and the blood coagulation analyzer is configured to select, for the purpose of calculating said blood coagulation time, a piece of light intensity variation data corresponding to one of the plurality of detectors (103a, 103b) suitable for securing a wide dynamic range and enhancing the sensitivity in the blood coagulation analysis from the multiple pieces of light intensity variation data, characterized in that the detectors (103a, 103b) are previously assigned priority orders, and when the amount of variation of the light intensity variation data from the selected detector (103a, 103b) of a high priority order is less than a preset threshold value, the light intensity data from the detector (103a, 103b) of the next priority order is selected for the calculation of the blood coagulation time, wherein the blood coagulation analyzer is further configured to calculate the blood coagulation time only from the light intensity variation data so selected. a reaction container which allows a reaction to occur in a liquid mixture of a sample and a reagent; a light source configured to irradiate the reaction container with single-wavelength light; and a plurality of detectors (103a, 103b) arranged around the reaction container at different angles with respect to an optical axis of the light source for detecting scattered light emitted from the liquid mixture of the sample and the reagent in the irradiated reaction container, the blood coagulation analyzer configured to calculate a blood coagulation time from chronological light intensity variation data detected by the detector (103a, 103b), wherein: the blood coagulation analyzer acquires and stores multiple pieces of light intensity variation data each corresponding to a respective one detector among the plurality of detectors (103a, 103b), and the blood coagulation analyzer is configured to select, for the purpose of calculating said blood coagulation time, a piece of light intensity variation data corresponding to one of the plurality of detectors (103a, 103b) suitable for securing a wide dynamic range and enhancing the sensitivity in the blood coagulation analysis from the multiple pieces of light intensity variation data, the blood coagulation analyzer acquires and stores multiple pieces of light intensity variation data each corresponding to a respective one detector among the plurality of detectors (103a, 103b), and the blood coagulation analyzer is configured to select, for the purpose of calculating said blood coagulation time, a piece of light intensity variation data corresponding to one of the plurality of detectors (103a, 103b) suitable for securing a wide dynamic range and enhancing the sensitivity in the blood coagulation analysis from the multiple pieces of light intensity variation data, characterized in that the detectors (103a, 103b) are previously assigned priority orders, and when the amount of variation of the light intensity variation data from the selected detector (103a, 103b) of a high priority order is less than a preset threshold value, the light intensity data from the detector (103a, 103b) of the next priority order is selected for the calculation of the blood coagulation time, wherein the blood coagulation analyzer is further configured to calculate the blood coagulation time only from the light intensity variation data so selected.