Motion of fingers of a subject is dynamically analyzed to provide an estimation index in a hardness of a muscle used in the motion of the fingers. A processing part calculates a speed and acceleration of two fingers on the basis of the motion data of the fingers obtained by a tapping detecting unit, calculates a ratio between the speed and the acceleration, and calculates as an estimation index a mechanical impedance regarding extending force of the fingers and a mechanical impedance regarding opening and closing force of the fingers by applying the calculated ratio to a predetermined equation based on a muscle dynamic model.
