Locking system for fixed ladder, in particular for camping vehicles

A rigid ladder which comprises at top ends hook shaped members (10) for being hung to a top edge of a vertical surface is provided with a locking system comprising a restraining block (20) which can be firmly connected to the vertical wall for housing said hook shaped member (10) and a locking cam (30) which secures the hook member (10) in its housing. The locking system is very simple and it allows the very safe use of the ladder.