Abstract: Invention patent for "Safety Lock" comprised by a mechanism (1) having a case composed of two parallel plates (2) interconnected by spacers (3), internally provided with an operating drive (4) for a latch bolt (5) and for a latch (6), this latter being also operable by means of a handle or alike, which passes through a corresponding opening (7), and, further, having a barrel block (8) incorporated in said mechanism (1) in transversal direction and being provided with a longitudinal hole or passage (9) which receives a puzzle barrel comprised by one or more rows of spring pin assemblies positioned radially with respect to two barrels (10) inserted in said passage (9), each of which has a cam configurating, eccentric and internal pin (11) which cooperates with the operating drive (4), said book (8) being retained within said mechanism by a drawer-like arrangement.