Robot system, robot controlling method, and semiconductor manufacturing system

A robot includes: a first arm that is a horizontal multi-joint type arm provided with a first base link provided to be rotatable around a pivoting axis, a first intermediate link, and a first hand that holds a workpiece W thereon, and configured to move the first hand along a first diameter direction; a second arm that is a horizontal multi-joint type arm provided with a second base link provided to be independently rotatable from the first base link around the pivoting axis, a second intermediate link, and a second hand that holds the workpiece W thereon, and configured to move the second hand along a second diameter direction, and a pivoting device configured to pivot the first arm and the second arm together in the circumferential direction while maintaining a positional relationship of the first arm and the second arm in the circumferential direction.