An instrument holder for fastening a medical instrument to an articulated arm, with: a body, a holder for holding the medical instrument on the body and a coupling element for attaching the body to the articulated arm, wherein the holder comprises: a threaded shaft provided with an outer thread, which shaft projects from a first contact surface formed on the body, a receiving disk which comprises a through hole via which the receiving disk can be inserted on the threaded shaft and can rotate about the threaded shaft, and a second contact surface which faces the first contact surface when the receiving disk is set on the threaded shaft, characterized in that the receiving disk comprises a receiving groove which is designed to receive a part (110, 112) of the medical instrument on a side of the receiving disk facing away from the second contact surface, and a locking element provided with an inner thread which element at least partially covers the receiving groove in the threaded engagement of its inner thread with the outer thread of the threaded shaft), as a result of which this part (100, 112) of the medical instrument is held in the receiving groove and can be tightened for a non-positive contacting of the two contact surfaces (66, 86) against the receiving disk, wherein a nose is formed on the receiving disk and projects laterally from the edge of the receiving disk and is designed to hold a U-shaped section of the medical instrument between itself and the body. a body, a holder for holding the medical instrument on the body and a coupling element for attaching the body to the articulated arm, wherein the holder comprises: a threaded shaft provided with an outer thread, which shaft projects from a first contact surface formed on the body, a receiving disk which comprises a through hole via which the receiving disk can be inserted on the threaded shaft and can rotate about the threaded shaft, and a second contact surface which faces the first contact surface when the receiving disk is set on the threaded shaft, characterized in that the receiving disk comprises a receiving groove which is designed to receive a part (110, 112) of the medical instrument on a side of the receiving disk facing away from the second contact surface, and a locking element provided with an inner thread which element at least partially covers the receiving groove in the threaded engagement of its inner thread with the outer thread of the threaded shaft), as a result of which this part (100, 112) of the medical instrument is held in the receiving groove and can be tightened for a non-positive contacting of the two contact surfaces (66, 86) against the receiving disk, a threaded shaft provided with an outer thread, which shaft projects from a first contact surface formed on the body, a receiving disk which comprises a through hole via which the receiving disk can be inserted on the threaded shaft and can rotate about the threaded shaft, and a second contact surface which faces the first contact surface when the receiving disk is set on the threaded shaft, characterized in that the receiving disk comprises a receiving groove which is designed to receive a part (110, 112) of the medical instrument on a side of the receiving disk facing away from the second contact surface, and a locking element provided with an inner thread which element at least partially covers the receiving groove in the threaded engagement of its inner thread with the outer thread of the threaded shaft), as a result of which this part (100, 112) of the medical instrument is held in the receiving groove and can be tightened for a non-positive contacting of the two contact surfaces (66, 86) against the receiving disk, wherein a nose is formed on the receiving disk and projects laterally from the edge of the receiving disk and is designed to hold a U-shaped section of the medical instrument between itself and the body.