A folding knife, including a handle and a blade. The handle has at least two parts connected to each other to form a cavity therebetween. The blade has at least one sharpened edge and a tang with an axial hole. The blade is rotatable around the axial hole between an open position, in which the sharpened edge extends outside the cavity and the tang is located inside the cavity, and a closed position, in which the sharpened edge and the tang are both located inside the cavity. The blade defines a first plane inside the cavity, and the tang further includes a step protrusion, a rounded protrusion and a radial perimeter extending between these two protrusions. An axial pin is inserted into the axial hole of the tang to rotatably secure the blade to a first end of the handle. A stop pin is attached to at least one of the two parts of the handle at the same first end of the handle within the cavity. The stop pin restricts movement of the blade in an opening direction. The folding knife also includes a locking member rotatably fitted onto the stop pin and located inside the cavity in the same first plane defined by the blade. The locking member is rotatable from a first position allowing the blade to rotate around the axial hole to a second position blocking rotation of the blade by engaging one of the tang's protrusions. The engagement of the locking member with the step protrusion of the tang locks the blade in its open position, and the engagement of the locking member with the rounded protrusion of the tang locks the blade in its closed position.