The utility model discloses a bullet drop prevention mechanism. The bullet drop prevention mechanism is movably connected with a bullet loader and includes a blocking part. A bullet head on the uppermost portion of a magazine located inside the bullet loader is blocked by the blocking part. The utility model also discloses the bullet loader including the bullet drop prevention mechanism described above. According to the bullet drop prevention mechanism, the problem that the uppermost bullet in a traditional bullet loader may drop out of the magazine is solved, not only loading of a bullet is not hindered, but also existing space of a traditional bullet loader is utilized, and no extra space is needed for installation.