Abstract: A locking device and a locking method are provided for a tool holder of a rotary drilling rig. The locking device includes a sleeve, a locking pin, a movement system, and a control system. The sleeve and the locking pin are configured such that the sleeve engages around the locking pin with a form fit, such that the locking pin can be rotated in the sleeve about the longitudinal axis of the locking pin. As a result, the locking pin can be displaced laterally parallel to the longitudinal axis. The movement system has at least one electric motor and at least one shaft, wherein the shaft effects relative rotation of the sleeve and the locking pin by the force of the electric motor.