To provide a bite prevention mechanism of hooking metal fitting mounted on a triple ladder and a hooking mechanism capable of speedily and securely performing hooking operation by a hooking metal fitting mechanism mounted on the triple assembly ladder for emergency and fire fighting and consisting of support fitting and pressing fitting stored in a box when a ladder body moves vertically and is hooked.

This hooking fitting mechanism is constituted such that the hooking mechanism consisting of the support fitting and the pressing fitting engaging with it and turning which are stored in the box at a first connection and a third connection is securely hooked in the support fitting protruding from a box opening part when the support fitting and the pressing fitting engaging with it are engaged due to the vertical movement of a horizontal bar for applying a foot of the ladder body when the ladder body moves vertically through elastic spring action in the box and are pushed back into the box and the ladder body is hooked to prevent biting.