To provide a locking device for sash for crime prevention excellent in crime preventiveness and capable of positively and firmly locking a crescent in a latching position.

This locking device for sash for crime prevention is provided with a locking frame 2 with a bent piece part 3 having a lock rod through hole 4 formed therein; a pad lock 10 having a hook-like lock rod 12 inserted through the lock rod through hole 4; and a cover 13 for integrally covering the lock rod 12. It is constituted so that, when locking the pad lock with the lock rod 12 inserted through the lock rod through hole 4, the bent piece part 3 is clamp-fixed between a pad lock body 11 and the cover 13, and the crescent 5 latched to a crescent latching member 6 is hindered from rotating in a latch release direction by the pad lock body 11.