The invention relates to relates to a bascule locking device for closing a flap pivoted on a frame, such as an opening on a container or a goods vehicle. Said device comprises a plate (1), a bar (2), a body (3), a handle (4) and a hook (6). The plate (1) is provided with a main clasp (11) and an auxiliary clasp (12). The hook (6) is operated by the handle (4) for locking to the auxiliary clasp (12) and for disengaging therefrom and the handle is mounted such as to pivot on the body (3) around the pivoting axis (5). According to the invention, the hook (6) is itself mounted on the body (3) such as to pivot about the pivoting axis (5) of the handle (4), without being fixed thereto.