A disposable shielded safety surgical scalpel, comprising: a blade (1), a handle (2), and a shield (3). When the shield (3) is slidably moved relative to the handle (2) and locked in a front position or a rear position, the blade (1) is respectively extended from or retracted into the shield (3). A locking mechanism comprises: a button (5) disposed at the shield (3), and a blade-shielding locking slot (7) and a blade-exposing locking slot (8) disposed at the handle (2). Lower portions of the blade-shielding locking slot (7) and the blade-exposing locking slot (8) are provided respectively with unlocking inclined surfaces (11, 13). When pressing and moving the button (5), a locking member (6) contacts the unlocking inclined surface (11, 13) and moves along the unlocking inclined surface (11, 13) so as to exit the blade-shielding locking slot (7) or the blade-exposing locking slot (8) to perform unlocking such that the shield (3) can slidably move relative to the handle (2) between the two locking positions of the blade-shielding locking slot (7) and the blade-exposing locking slot (8). The present invention represents a significant advance over conventional positioning mechanisms, improves the safety of a surgical scalpel, and provides a better feel and auditory experience when using the surgical scalpel.L'invention concerne un scalpel chirurgical de sécurité blindé jetable, comprenant : une lame (1), une poignée (2) et une protection (3). Lorsque la protection (3) est déplacée de manière coulissante par rapport à la poignée (2) et verrouillée dans une position avant ou une position arrière, la lame (1) est respectivement déployée depuis la protection ou rétractée dans la protection (3). Un mécanisme de verrouillage comprend : un bouton (5) disposé au niveau de la protection (3) et une fente (7) de verrouillage protégeant la lame et une fente (8) de verrouillage de faisant apparaître la lame disposée au niveau de la poignée (2). Des parties inférieures de la fente (7
