The present invention concerns a padlock (100) comprising : - A case (103); - An arc (102) assembled mobile with respect to the case (103) between an open position and a close position; - Means (105, 150, 106, 180) to block the arc (102) in said close position and unblock it, allowing it to turn to the open position. In accordance with the invention, said means (105, 106, 180) comprise a cylindrical device (105) assembled in a rotatable manner in the case (103) and forming a cam (150), said cam being cooperating with a retaining device (106) lodged in the case (103), and provided with a tooth (107), mobile, and configured in such a way that, through a rotation of the cam, said tooth (107) moves between an extended position, in which it engages with the arc (102), and a retracted position, in which it disengages from the arc (102), and vice-versa.