A latch device (30) for a door lock includes a latch (38) pivotable between an extended, locking position and a retracted, unlocking position upon operation of a linking rod (37). A liming block (36) is coupled with the linking rod (37) and movable between a locking position not allowing direct pivotal movement of the latch (38) from the extended position to the retracted position and an unlocking position allowing pivotal movement of the latch (38) from the extended position to the retracted position. When the door is closed, the locking member (36) is moved by gravitational force to a locking position. Movement of the linking rod (37) in an unlatching position through an idle travel moves the locking member (36) from the locking position to the unlocking position without moving the latch (38). Further movement of the linking rod (37) in the unlatching position causes pivotal movement of the latch (38) from the extended position to the retracted position.