In a robot hand according to the present invention, a first-type grasping
claw driven by a servo motor on a hand base and a second-type grasping
claw having no actuator are used with the grasping claws mounted on each
holding unit. The second-type grasping claw is movable in a direction
perpendicular to a moving direction of the first-type grasping claw. The
robot is operated so that an external force is applied to the grasping
claw by bringing the grasping claw into contact with a contact surface of
a stationary stand member, thereby to change a position of the grasping
claw relative to the hand base and that grasping claw is locked at that
position by a brake mechanism. Each grasping claw is adapted to be able
to be mounted or dismounted on or from the holding unit using a pull bolt
and a retaining mechanism, and can be automatically changed by the robot
operation. By attaching the pull bolt to the workpiece in advance, the
retaining mechanism also can be used for holding the workpiece.