To definitely prevent forgetting due to misbelief by providing a constitution with which a key cannot be turned unless a door is fully closed and a trigger plate has not been pushed into a fixing case.

When a cam sloped surface portion of a trigger plate 9 is projected out from a fixed case 1, a flat surface portion 12a of an operation plate base end portion 12 is contacted to a belly 9a of an inner end portion of a trigger plate 9. Because of this, the rotation of the operation plate 6 is blocked and thus a latch 3 cannot be stuck out and moved to a locking position by turning a rotor with a key. Thereafter, when the door is fully closed and an escape groove hole 13 of the trigger plate 9 is pushed to a position opposite to a flat surface portion 12a of the base end portion 12 of the operation plate, then the key can be now turned. That is, if the key can be turned, this means that the door is completely closed. Thus, the forgetting of locking door due to misbelief can be definitely prevented.