A robot hand, comprising: a planetary gear unit to which a rotational power from a power source is input; first and second drive shafts (3,4) to which a rotational power output from the planetary gear unit is transmitted; and a finger including a first joint driven by the first drive shaft, a first finger element mounted on a fingertip side of the first joint, a second joint mounted on a fingertip side of the first finger element and driven by the second drive shaft, and a second finger element mounted on a fingertip side of the second joint; wherein the planetary gear unit includes a sun gear, a planetary gear meshing with external teeth of the sun gear, a planetary arm connected to the planetary gear so as to move coordinately with a rotation of the planetary gear around the sun gear, an internal gear meshing with external teeth of the planetary gear so as to move coordinately with a rotation of the planetary gear on its own axis, wherein one of the sun gear, the planetary arm and the internal gear is used as a power input part, and remaining two thereof are respectively used as a first power output part and a second power output part, wherein the power input part is connected to the power source in a way that a power can be transmitted, wherein the first power output part is connected to the first drive shaft in a way that a power can be transmitted, wherein the second power output part is connected to the second drive shaft in a way that a power can be transmitted, and wherein the robot hand is further provided with a resistance generating unit configured to make a motion resistance of the second power output part lager than a motion resistance of the first power output part. a planetary gear unit to which a rotational power from a power source is input; first and second drive shafts (3,4) to which a rotational power output from the planetary gear unit is transmitted; and a finger including a first joint driven by the first drive shaft, a first finger element mounted on a fingertip side of the first joint, a second joint mounted on a fingertip side of the first finger element and driven by the second drive shaft, and a second finger element mounted on a fingertip side of the second joint; wherein the planetary gear unit includes a sun gear, a planetary gear meshing with external teeth of the sun gear, a planetary arm connected to the planetary gear so as to move coordinately with a rotation of the planetary gear around the sun gear, an internal gear meshing with external teeth of the planetary gear so as to move coordinately with a rotation of the planetary gear on its own axis, wherein one of the sun gear, the planetary arm and the internal gear is used as a power input part, and remaining two thereof are respectively used as a first power output part and a second power output part, wherein the power input part is connected to the power source in a way that a power can be transmitted, wherein the first power output part is connected to the first drive shaft in a way that a power can be transmitted, wherein the second power output part is connected to the second drive shaft in a way that a power can be transmitted, and wherein the robot hand is further provided with a resistance generating unit configured to make a motion resistance of the second power output part lager than a motion resistance of the first power output part.