A thrust reverser device for a turbojet engine nacelle includes a cowl mounted translating between a closing position and an opening position in which the cowl opens a passage in the nacelle and uncovers deflecting cascades. The cowl is associated with a blocking flap pivotally mounted on the cowl between a retracted position and a pivoted blocking position in which the blocking flap closes partially an air flow path of the nacelle. The blocking flap is equipped with a driving mechanism including an assembly forming a lever pivotally mounted on the cowl and articulated at each of ends of the lever, by means of driving links, respectively on the blocking flap and on a fixed structure of the thrust reverser device. In particular, the assembly and the driving links are articulated in an articulation plane substantially perpendicular to the blocking flap and substantially radial to the thrust reverser device.