PURPOSE: To eliminate various inconveniences caused by an inclination of a large piece in a latch lock due to an external force exerted upon locking, by engaging lock pine which are extended from the top and bottom of the latch piece, in elongated holes formed in upper and lower guide plates.

CONSTITUTION: A pair of upper and lower guide plates 8 are fixed in a lock casing 1. A latch piece 4 is interposed between the guide plates 8 so as to be extractable and retractable, and invertible. A spring 15 for urging the larch piece 4 forward so as to engage the same into a locking hole formed in a door attaching frame is provided in the casing 1. Cranks 16 which are vertically swung about shafts 17 are provided in the upper and lower parts of the inside of the casing 1, a pressing piece 18 for pressing a lock pin 10 which is therefore released from an elongated hole 11 is provided at the front end of each of the cranks 16. Both cranks 16 are associated with each other so that they are moved when a movable handle attached to a door is moved.