Active positioning device of a surgical instrument for use on a robotic arm comprising a support plate (3, 33) which can be connected to a robotic arm (1, 31), a port device (4, 34) which is arranged on the support plate (3, 33) and which is provided for the passage to the inside of a body, at least one guide device (6, 36, 59) for guiding a surgical instrument (8, 38, 61) through into the body, wherein the shaft of the surgical instrument (8, 38, 61) extends through the guide device (6, 36, 59) and wherein the guide device (6, 36, 59) is variably connected to the port device (4, 34) via a compensating element (5, 35), and an adjustment device (9, 10, 11, 12, 13, 14, 39, 40, 41, 42, 43, 44, 62, 63, 64, 65, 66, 67) for the guide device (6, 36, 59) relative to the port device (4, 34), which is attached on the one hand to the support plate (3, 33) and/or the port device (4, 34) and on the other hand to the guide device (6, 36, 59) such that the shaft of the surgical instrument (8, 38, 61) is movable about a pivot point both in the x-direction and in the y-direction, which is orthogonal thereto, relative to the starting position in which the longitudinal extension of the surgical instrument, which defines the z-direction lying orthogonal to the x-direction and y-direction, runs parallel to the longitudinal extension of the port device (4, 34), wherein the adjustment device (9, 10, 11, 12, 13, 14, 39, 40, 41, 42, 43, 44, 62, 63, 64, 65, 66, 67) has two controllable actuators (9, 12, 39, 42, 62, 65) which are designed as actuating drives (9, 12, 39, 42, 62, 65) arranged orthogonal to each other, wherein a ball lever mechanism (10, 11, 13, 14, 40, 41, 43, 44, 63, 64, 66, 67) is provided between the guide device (6, 36, 59) and the support plate (3, 33) or the port device (4, 34) such that the guide device (6, 36) can be positioned relative to the starting position in the x-direction and y-direction independently of each other by the actuating drives (9, 12, 39, 42) by means of the ball lever mechanism (10, 11, 13, 14, 40, 41, 43, 44). a support plate (3, 33) which can be connected to a robotic arm (1, 31), a port device (4, 34) which is arranged on the support plate (3, 33) and which is provided for the passage to the inside of a body, at least one guide device (6, 36, 59) for guiding a surgical instrument (8, 38, 61) through into the body, wherein the shaft of the surgical instrument (8, 38, 61) extends through the guide device (6, 36, 59) and wherein the guide device (6, 36, 59) is variably connected to the port device (4, 34) via a compensating element (5, 35), and an adjustment device (9, 10, 11, 12, 13, 14, 39, 40, 41, 42, 43, 44, 62, 63, 64, 65, 66, 67) for the guide device (6, 36, 59) relative to the port device (4, 34), which is attached on the one hand to the support plate (3, 33) and/or the port device (4, 34) and on the other hand to the guide device (6, 36, 59) such that the shaft of the surgical instrument (8, 38, 61) is movable about a pivot point both in the x-direction and in the y-direction, which is orthogonal thereto, relative to the starting position in which the longitudinal extension of the surgical instrument, which defines the z-direction lying orthogonal to the x-direction and y-direction, runs parallel to the longitudinal extension of the port device (4, 34), wherein the adjustment device (9, 10, 11, 12, 13, 14, 39, 40, 41, 42, 43, 44, 62, 63, 64, 65, 66, 67) has two controllable actuators (9, 12, 39, 42, 62, 65) which are designed as actuating drives (9, 12, 39, 42, 62, 65) arranged orthogonal to each other, wherein a ball lever mechanism (10, 11, 13, 14, 40, 41, 43, 44, 63, 64, 66, 67) is provided between the guide device (6, 36, 59) and the support plate (3, 33) or the port device (4, 34) such that the guide device (6, 36) can be positioned relative to the starting position in the x-direction and y-direction independently of each other by the actuating drives (9, 12, 39, 42) by means of the ball lever mechanism (10, 11, 13, 14, 40, 41, 43, 44).