To provide a hook bolt lock capable of effectively utilizing a limited space of a lock box by rationally incorporating a latching mechanism and a locking piece, etc. into the lock box and completely locking a latch plate of the latching mechanism so that the sliding door can not be moved by a human factor in a temporary locking state.

In the hook bolt lock respectively equipped with a trigger retreated into the lock box by hitting against a receiving metal fitting on the side of a door frame when the sliding door is closed and a sickle piece pivoted on a fixed axis and rotating in the direction engaged with the receiving metal fitting by interlocking with a retreat motion of the trigger, the latching mechanism Z equipped with the latch plate engaged with one of a plurality of temporary fixing engaging parts formed in one side of the trigger is placed in the lock box, on the other hand, when a temporary locking engaging the latch plate with the temporary fixing engaging parts is made, the hook bolt lock is so constituted that it is slid by operating force of an operating member to engage with a locking arm engaging with the trigger and that a locking piece having a prevention part preventing the rotation of the latch plate is placed to adjacent the latch plate.