Abstract: A measuring technology of sedimentation rate of sediments in a liquid sample capable of measuring, for example, the sedimentation rate of erythrocytes in a patient requiring an urgent medical treatment in about ¼ of the time needed in the conventional measuring method, and also capable of measuring the sedimentation rate of erythrocytes in an infant limited in the blood sampling volume. A test container filled with a liquid sample is inclined and held at a specific inclination angle, light is projected to this test container, the light passing through the test container is electrically detected by a line sensor or the like, the liquid level of the supernatant in the liquid sample and the position of the boundary of the supernatant and sediments are calculated to obtained the depth of the sediments, and the sedimentation rate of the sediments is calculated from the depth of the sediments and the measuring time.