A heel piece of a safety binding for a ski boot that is able to occupy at least two positions, an open position and a closed position in which it is able to hold a ski boot securely for skiing, the heel piece comprising a body (11) that occupies the same position in each of these two positions of the heel piece, the body (11) comprising a release mechanism to allow the boot to be released in the closed position of the heel piece if a force exceeds a predetermined level, the heel piece further comprising a lever (12) comprising jaws (14) in its anterior part, these being able to collaborate with the heel of a ski boot, the lever (12) being mounted so that it can rotate relative to the body (11) about a pivot (13) so as to occupy two different positions corresponding to the two, open and closed, positions of the heel piece, wherein at least one end of the pivot (13) is held near the body (11) of the heel piece.