A method for measuring a degree of deformation of blood cells includes: supplying blood to a centrifugal container of a disk; centrifuging the blood in the centrifugal container to blood cells and plasma by rotating the disk and detecting an actual moving distance of the blood cells in the centrifugal container every hour; and calculating a first curve representing the actual moving distance of the blood cells in the centrifugal container every hour and a second curve representing a theoretical moving distance of the blood cells every hour and measuring a degree of deformation of the blood cells by comparing the first curve and the second curve.