A robotic arm includes a driving unit, a first arm assembly connected to the driving unit, and a second arm assembly. The first arm includes two balls. The second arm assembly includes two arms and two intermediate members. Each intermediate member is secured to an end of one of the two arms. Each intermediate member defines a receiving recess. Each receiving recess has a spherical inner circumferential surface. Each ball is partially received in one of the two receiving recesses and abuts against the spherical inner circumferential surface. The two arms and the two intermediate members are capable of rotating about the balls. The driving unit drives the balls to move. The balls force the arms to move in a direction as a moving orientation of the balls, at the same time the arms rotating about the balls.