A lock, adapted for being assembled on a door panel, is provided. The door sheet has an assembling hole and a latch slot connected and communicated with the assembling hole. The lock includes a latch assembly, a first locking mechanism, and a second locking mechanism. The latch assembly is assembled in the latch slot and extended into the assembling hole. The first locking mechanism and the second locking mechanism are assembled in the assembling hole from the two sides thereof respectively to automatically position and affix the latch assembly. Because the latch assembly can be to led to move and positioned in the latch slot and the assembling hole by the first locking mechanism and no screw or other tool are required for fastening in the entire process of the assembling, the present invention is therefore easy and convenient to assemble.