Abstract: A hitch lock device for preventing theft of a trailer featuring a hitch ball with a threaded bolt and a nut adapted to be threaded onto the bolt. Locking pin slots are disposed in the threaded bolt. A lock can be inserted into a slot in the threaded bolt. Locking pins are slidably disposed in each locking pin slot. The locking pins are connected by a spring and can move between an in position in the threaded bolt and an out position protruding from the bolt. The pins are biased in the out position by the spring. When the locking pins are squeezed to the in position the nut can be threaded past the locking pins to sandwich a trailer hitch with the hitch ball. When the lock is inserted into the slot the lock blocks movement of the locking pins and locking the lock prevents removal of the lock.