An instrument support device for a manipulator of a robotic surgical system, comprising: an arm having first, second and third arm elements； an interface for connecting the first arm element to the manipulator via a rotational joint； a torsional joint connecting the first and second arm elements； a first rotational joint connecting the second and third arm elements； a sliding joint connecting the third arm element to an instrument mounting for receiving a surgical instrument with a longitudinal axis； and a controller with drives for moving the arm elements and instrument mounting. The instrument mounting is connected to the third arm element via a second rotational joint, the rotational axes of the first and second rotational joints lie parallel to each other, and the longitudinal axis is guidable through a pivot point on the rotational axis of the torsional joint in an extension from the second arm element, without constraint.
