The present invention relates to a tip protector device for a medical instrument, such as an endoscope or borescope. The tip protector device according to the present invention comprises a housing configured to releasably receive a tip of a medical instrument, a clamping system configured to retain by clamping the tip received by the housing in a retaining position and a locking system configured to perform a locking step, wherein the locking step comprises, successively, the locking and unlocking of the clamping system in the retaining position. The tip protector further comprises a blocking element, wherein the blocking element is configured to block the locking system after repeated use of the device. The present invention also relates to a method of protecting the tip of a medical instrument.