A robot hand includes a pair of movable members that is detachable from a wrist flange of a robot body and that are arranged at a distance from each other; holding parts that are provided on the movable members and that hold a workpiece; and a width adjusting mechanism that supports the pair of movable members so as to allow relative movement thereof in a width direction and that adjusts a distance B between the pair of movable members by means of the relative movement of the pair of movable members in the width direction (A). The pair of movable members are relatively moved in the width direction as a result of the width adjusting mechanism.