A nail shape acquiring device has a control unit, which acquires a plurality of index values representing a degree of curve of a curved shape of a nail of each of a plurality of objects on the basis of at least one image in which the plurality of objects is imaged. The plurality of objects are a plurality of fingers, including at least one pair of same type fingers on right and left hands, or toes, including at least one pair of same type toes on right and left feet. A determination unit determines, on the basis of different index values for nails of the same type fingers or the same type toes, whether at least one of the index values is to be used as a value representing the degree of the curve of the curved shape of the nail.