Robot hand, robot apparatus, and method of controlling robot hand

A method of controlling a robot hand that includes three or more finger units and grips an object by the finger units, the robot hand including a driving mechanism, a pivoting mechanism, and a control unit, the driving mechanism causing the three or more finger units to independently approach one another or independently separate from one another, the pivoting mechanism turning two or more of the three or more finger units to change an approaching direction or a separating direction of the two or more finger units, and the control unit controlling the driving mechanism and the pivoting mechanism, the method comprising:

• gripping the object with use of at least two of the finger units;
• and
• assembling the object to another object by, in a state where the object is gripped by two or more of the finger units, not operating the two or more of the finger units used for gripping the object but operating one or more of the finger units other than the two or more of the finger units in an assembling direction and moving the object in the assembling direction.