The manipulating action of the lesser panda (Ailurus fulgens) was quantitatively analyzed by the CT and three-dimensional digitalized techniques. The forearm, metacarpals, radial sesamoid bone and accessory carpal bone were considered as movable parts in the simulation of the dead body, and we examined the change of angles among these four segments in the grasping action. In the manipulation the radial sesamoid bone moved independently from the metacarpals in the lesser panda. It was not articulated to the first metacarpal bone, but supported by some muscle tendons and the other soft parts of the wrist and palm regions. Although the grasping apparatus consists of the functional units of the radial sesamoid bone and accessory carpal bone in the giant panda (Aliluropoda melanoleuca), the manipulating mechanism using the radial sesamoid bone in the lesser panda had no functional-morphological similarities to that in the giant panda. The radial sesamoid bone as a manipulating tool of the lesser panda has been developed in the separated evolutionary history of this species.